Can't won't stop scratching (picture warning)

[PeanuttyButter]

Black cat, everytime this time of year gets extra itchy. We are on too of worming/flea/mite protection as have a subscription with the vets. It's always this time of year she starts scratching to the point she scratches herself raw.
Usually it scabs over, she's scratches the scab off once or twice but then it heals.
Vet seems to think it's an allergy/irritation to some seasonal plant/pollen.
This year doesn't seem to be healing and it's a huge patch now. Over an inch wide and about 3 inch long. It's also bleeding now and covering her surrounding fur.
Any ideas on how we can help it heal? Or stop her scratching

Ooh, poor wee soul, that looks painful .

I'd take her back to the vet. I don't know if they still do this as it's been a long time since I've had an itchy pet, but they used to give ours an injection which stopped the itching almost straight away. Might need antibiotics too.

Give her a wee kiss on the head from me.

Honestly, if you have to put a warning about the picture, it's time to go to the vet.

Harvest mites? My mums cat used to suffer this time of year.

You need to get her to the vet. If it is something outside she is allergic to why on earth are you letting her out when you know this will happen?

I'd be dressing that and sticking her in a ln item or baby clothing to stop her getting at it. She needs a vet really, that looks sore and her overall condition looks poor.

My cat is the same, he will itch himself raw and pulls all his fur out. Some kind of environmental trigger but no one seems to know what. The drug that has made the difference for him is Apoquel. I suggest a trip to the vets, that looks really sore.

Needs a steroid and antibiotic injection!

@utterlyunimaginativeusername I put the warning up to protect those who don't like the sight of blood etc. I work in the medical field so my tolerance is high with regards to this kind of thing.

@ZeroFuchsGiven because if we try to keep her in she injures herself trying to get out. She will not use the house litter tray only the one in the shed. Also as I said pervious usually when this happens on an annual basis she is fine after a day or two (it's not usually this bad)

Thank you @gamerchick and @TheGonnagle that's the kind of advice I'm looking for. I have contacted the vets (as I do every year) and waiting for them to get back but was hoping to have some help in the interim. Or at least a plan when I go to the vets

Also the person querying her condition and why we've let it get so bad.
She went out on Monday after breakfast (we live near fields) and didn't return until last night which is unlike her. We've been worried sick and haven't seen the progression.

This was her the day before she started scratching and then 2 years ago I crocheted her a onesie/neck cover. But didn't help

I love the pictures and the crochet top!!

My friend has 3 cats - mum and 2 children. They all suffer in the summer with this. She has taken them to the vets over and over. She has been told an allergy to something.