Help! I'm not sure what to do

So basically, I'm in the middle of my A-Level exams (I had one on Wednesday and today so far this week) and i have sociology tomorrow morning but I have come down with some kind of fever/vomiting bug. I didn't feel great the last few days but pushed myself through it and now have come home and just been throwing up for most of the night. I'm really stressed now as I planned (and need to!) revise tonight, but more importantly, I'm really worried about sitting my exam tomorrow.

I've had bugs like this before and they usually last for a few days and so I'm kinda worried I won't be alright to sit the exam.

Part of me wants to force myself through it but like at the same time I'm rn struggling to last 10 minutes standing up/walking around etc without throwing up so I'm not sure how easily I can sit the exam

I'm confused tho whether I am able to miss it? Like I don't want to but if I sit it and literally can't write much/perform to my normal standard yet it is marked as if I were well, then that will largely affect my grade.

What do I do?

Should I let my school know, but then I think I need a doctors note but I'm not really sure how I go about getting that - like do i go to the doctors just to prove I'm sick???

Does anyone know from experience how this works? I really don't want it affecting my grade in this subject as I have been quite consitent overall - would I have to sit the exam and just get special consideration overall or do I/am I allowed to miss the exam altogether and still make up for the mark in my last exam (this one would be paper 2 btw)

Oh, also I do AQA

But yeah, someone help, the rules and regulations of exam boards kinda scare me and I dont want to do anything wrong

thank you