Anything relaxing, maybe Deep Relaxation, so you can relax at will, not to fall asleep, but so you can control your tense feelings in exams.
As you seem to believe that you will feel tense or panicky in exams, maybe something like Belief or New Option Generator would help you create a better picture of how you will feel.
What you are describing sounds a lot like a panic attack. These are no fun at all, but they can be overcome.
Good luck!
Jodi