I can appreciate your being nervous. However, try to look at it from another point of view. Either one of two GOOD things are going to happen. (1) the tests will show that you're OK, or (2) the tests will identify a problem, what that problem is, and what treatment is necessary to make you well. So either way, the outcome will be good. You're either fine, or you're going to be fine.
May I ask your age?