This is too much. You should really seek out some counseling or something. I'm not being facetious - please get help. If you are this stressed about high school grades you will really struggle with college and especially med school, and you should learn better coping skills before this anxiety negatively affects your life and career. High school grades literally do not matter in the grand scheme of life. As long as you're doing the best you can, you should not be feeling like you're on the edge of a skyscraper because you're getting an 85 in high school math. You're doing fine.
I was kind of exaggerating, but I really do feel that way before tests sometimes. Regularly I have either mild anxiety or stress and sometimes I'm perfectly fine. And the worst is like depression RANDOMLY.
Please stop using this word the way that you've used it, particularly if you would like to be a physician someday which will involve working with people with all kinds of disabilities.