Welcome to PC!! Really sorry you are struggling. I admire your efforts to stay in school with these issues.
There should be disability services for people who need to take test away from the large classroom. You will probably need some kind of paperwork from your T or pdoc for this.
If you don't mind me asking, have you seen a neurologist about these symptoms you speak of??
Don't know if this helps, just nice to know someone read your post.

Take care of yourself, don't give up.