I have a similar problem. Since my first days of standardized testing in 2nd grade, it was clear that I had test anxiety. That's when I got my first bald patches from pulling my hair out, during testing time.

There is something you can get called a technical-504. It's basically protection from the federal government against discrimination from teachers that allows you to have accommodations for your needs. I have one and it's really helped. Those individual accommodations depend on what help you or not. To get the 504 you have to have a meeting with your school's supervisor(s) and have proof (like a diagnosis) as to why you need them.

Good luck!!