When you say burning, do you mean actually burning? Or is it like a metaphor?
It makes sense that we picture ourselves as being in our “head”, after all that’s where all the thinking comes from (our brain). But, our whole body is really involved when we get stressed or anxious. Our heart rate and blood pressure can increase, and many other things. It may be that you are getting so stressed that it’s causing you pain (I’m not a doctor though so this is not a diagnosis).
You know what? From what I’ve heard, you sound anything but dumb. On the contrary you seem very intelligent- you’ve outlined many possible ideas to move forward. Life is full of difficult choices, and you’re actually thinking hard about them - unfortunately for your emotions. Anyone who has experienced anxiety over study has wanted to not feel, or think, or be annoyed. Let me tell you from personal experience I have felt that very often. And I am 30 now: I went and got a Bachelor of Music at University, then didn’t use it and took a break and just last year finished a degree in Psychology after studying part time for years. And I’m still studying with it, so I know intimately what you mean. I have much to share on that front.
I think physics would be hard - i didnt choose it or bio or chem as a school student, but chose things I felt I would be able to do. I would actually love to pick it up to understand it better as an adult, maybe one day.
None of this is to say you should or shouldn’t drop physics.
Could it be that the anxiety you’re experiencing is due to two things: (1) this big choice you’re thinking of making (changing classes), and (2) the fact that it’s difficult to study in a noisy environment?
If so, There’s two chunks you can split your problem up into.
Also, Have you mentioned any of this to your parents? Friends?