Oh OP I was just about to start a thread about this sort of thing, I know exactly how you feel and you are absolutely not being unreasonable. Here to hand hold and offer a bit of advice.
Ok so DS was poorly last week with a high temperature that we struggled to control with Calpol (above 40). We took him to the walk in clinic when he started to shake (rigours, not convulsions) and they explained things to me which helped to settle my mind. A temperature of up to 39 is fine when a child is ill, it means the body is doing what it should be doing to fight the infection. Calpol and/or ibuprofen can be given to make the child more comfortable but it's ok to leave the temperature if it's settled at that point.
If the child shakes it's the body trying to warm itself up faster, it's important to get to medical help at this point but when it's caused by a usually harmless infection (like tonsillitis or an ear infection) it's not too much of a worry once they're on their way to a dr. Calpol/ibuprofen can be used to control it so should definitely be given at this point.
Even if the temperature leads to convulsions, these in themselves are not dangerous and are some children's natural reaction to temperatures. I feel like a hypocrite saying this because I can't imagine how awful it must be to experience this but once a dr had said this to me it really helped me to calm and prepare myself, I was much more capable of looking after DS knowing that a lot of it was 'normal'.
A dr can give you a dosage guide of Calpol and ibuprofen based on your DD's weight so you know you're giving her exactly the right amount. You can combine the two but this really has to be guided by a dr/nurse as they will know what works but they advised us so that we were giving something every 3 hours if his temperature was shooting up before the last dose of one was up (this was under their guidance and we wouldn't do it otherwise so dont do it - I've included this so that you know there are other things they can do, don't think that medicine isn't working). Please don't hang about waiting for that call back, go to a walk in clinic or even A&E and they will help you. It's more than likely it's nothing serious but the stress of the situation, considering recent events, means you could use some support and these places will be more than happy to help you.
It's awful, but I promise you it does happen to everyone despite it feeling like a lonely time. Don't use cold flannels/baths etc, make sure she's not in a draught but keep the room cool and offer fluids regularly.
I hope she's feeling better soon and that you are too. X