Can anxiety and depression really do all this?

Sounds like what happened in your senior year was a panic attack. What you are experiencing now is extreme, severe anxiety. It's OK to have the thoughts you are having, but your thoughts are producing fear, which in turn produces anxiety. Please consider talking with a mental health professional. You may need some counseling and some medication. I know personally that your kind of anxiety could lead to severe depression. You don't want that. Good luck!!