To think there must be something that can help DD?

My brother was the same. If it was planned he would work himself into a frenzy leading up to it, resulting in him throwing his guts up and not end up going. If it was spur of the moment he was absolutely fine as he didn't have that time to worry about things (missing train, gettinglost, lots of people there ect). It was the worrying and whittling he did in his head that lead to his anxiety and him being sick. He eventually told me he used to worry so much he would throw up, that's exactly what he did. He was diagnosed with dependent personality disorder (DPD) when he was 25.

Sounds like cyclical vomiting. ..

This might be way off, but rather than trying to prevent the sickness or avoid the nausea, just for the next little bit of time, and you could both set a time limit, like one calendar month, could she perhaps try "radical acceptance" and push through?
Small plans only, like going for a walk with you or her best friend.
Yes, she's going to feel sick.
Yep, she might be sick.
It is awful and no one pretends it isn't.
But once she has vomited, she gets her shoes on and there is already sick bags, mints, and water in a bag that is by the door, and she just goes.

I appreciate you say she gets hysterical, and it might not work the first time, but as her mother and with her really clinging to childhood and that bond you share, it could help if you dig your heels in and find the grit for both of you - even if you just get to the end of the driveway. And then you celebrate it!

Massive hug, positive reinforcement, and lots of rest. And then the same thing the next day. A trip out is planned in advance, the nausea creeps in, is acknowledged, treated as a tedious chore, and then afterwards you all just go for it anyway.

Good luck @Owwdi 💖

it sounds to me like chronic anxiety state of GAD(general anxiety disorder)
unintentionally she has got herself in a vicious circle , because it’s happened a few time now, her mind has become used to it happening that as soon as she’s out of her comfort zone's it brings the sickness on , then because her anxiety is heightened she get nauseous, because that’s hanging about, it triggers the sickness
so
out of Comfort zone
heightened anxiety
anxiety causes nausea
nausea heightens her anxiety more
hence sickness

when her anxiety lower’s does the sickness stop ?

Oh and also hypermobility of joints is linked with autism and also PoTS so worth doing a Beighton score if there's any suspicion she's hypermobile.

Has she been screened for postural tachycardia syndrome (pots)? It causes chronic fatigue and physiological (as opposed to psychological) anxiety due to the heart racing and activating the fight or flight response. It can also cause digestion to slow down (something like gastroparesis) meaning people can feel chronically nauseated. My sister who has pots and is autistic tells me there is a strong link between PoTS and neurodivergence.

Sertraline can actually help the physiological anxiety side by it's effects upon the autonomic nervous system (i.e. parts of nervous system outside your active control eg digestion/squeezing of blood vessels when you stand).

If she's not been screened, could she have a 10 minute stand test through the GP surgery? Sertraline would influence the result but if her heart rate went up by 30 beats per minute without a drop in blood pressure, she could ask to be referred for pots treatment e.g. beta blockers or ivabradine. Getting in control helps the nausea and 90% of people with pots respond to treatment to varying degrees.

A certain proportion of people with PoTS also have what's called mast cell activation syndrome or MCAS. For patients with PoTS and allergic type symptoms or strange rashes, they can sometimes be recommended to take a daily non-drowsy antihistamine e.g. cetirizine or fexofenadine. This can be hugely helpful with their chronic fatigue/nausea symptoms.

From what I have seen, many people with physiological anxiety caused by activation of the fight or flight response become phobic or attribute symptoms to a psychological cause. This is because it is very difficult to feel physically anxious without trying to find a reason for why you feel the way you do.

Sounds very similar to my ND teenage son who was diagnosed with stress/anxiety induced cyclical vomiting syndrome as a child.

Could be way off here but just a thought: have you seen this sickness taking place? Is there a chance she’s making herself sick? Not to be deceptive or anything like that, but either as a manifestation of an ED or as some sort of physical outlet for anxiety/a reason to not attend a social event she is nervous about, even if some of her really wants to go. If she’s torn with wanting to go to X place but has crippling anxiety about doing so, could she be inducing vomiting as an ‘out’?

I had something similar as a teen. It was related to work, just starting a new job and I would throw up for hours before work. The only thing that helped was basically forcing myself to do it. Every single day. Just getting up and going and just throwing up and keep on going. As hard as it is she just needs to force herself to do the things

I had this from I was around 6-20 and it was social anxiety every Christmas/birthday/party/social gathering I would be vomiting all day, the only thing that helped was getting anxiety under control (to an extent)

From what you have said it sounds like long standing anxiety - maybe related to ND

a trigger situation where she was nauseas / sick - on a relatively long holiday a long way from home - I’m sure that was very overwhelming

then the development of an anxiety disorder - related to fear of nausea / vomiting / losing control when away from home - social events -

so almost a mix of social anxiety / panic disorder and emetephobia -

her anxiety will lead to nausea of course, which leads to more anxiety …

I would suggest a medication review -
as PP said she is on a barely therapeutic dose of an SSRI - she may benefit from trying another one at a more effective dose
and change therapist
you need one who understands emetephobia- which is one of the more complex anxiety disorders - and will be used to tailoring therapy for ND -

best wishes

It's of course entirely up to you and I wish your daughter well but if there is a chance it could have a physical cause and there is her situation is virtually identifical to mine I just don't understand why you wouldn't push to rule out all physical causes before assuming it is anxiety.

Anyway wish your daughter well from me I know what it like to be her and it is miserable I wish someone had told me that it could be physical 20 years ago but like this thread everyone assumed anxiety.

I'll bow out

I was going to suggest this anyway, but given her CFS too, then I definitely think she’d do well to try Pregabalin, principally for extreme anxiety, for which it is quite shockingly effective.
But it’s very good with pain and for energy loss too.
[It has drawbacks/risks but I believe that these are well worth it when your whole life is st a standstill snd very much stuck]
Certainly that Sertraline isnt doing any good at all.
Personally I’d ditch, or definitely change, the therapist too.

If the GP is against long term anti sickness, is it possible to get some and after she's had a few and they've worked mix in some type of tablet that looks similar but not dangerous to take obvs and see if the placebo affect would work? Given it sounds psychological then if she doesn't know the tablet shes taking isnt actually an anti sickness then hopefully just the act of taking the placebo would help?

Oh bless her. My teen DD is a bit like this. She can only manage college, which is literally on the doorstep and one shop when she knows it'll be quiet.

That won't show up if the issue is something like a hernia. I was written off as being anxious for so long it ruined so many experiences I would push for more tests