I am sorry you feel so bad. But you're hurting yourself. And I wish you'd stop. I can't make you, but I wish you would stop doing that.
It's ok to be stressed and even overwhelmed, but hurting yourself like that won't make those stresses go away. I hope your exams go well and that you get through this. I'm sure you will.
Please get yourself help if you can. I imagine you need to be in therapy too. I just don't want you to hurt yourself anymore.