I'm going crazy, I need help.

I've realised that this year, my life's revolved around me studying for exams and tests and for some reason I can't seem to stop. I think I might have a problem.
I'm afraid to not study for an exam because I fear I will fail...which is understandable...but I do take it to the extreme where that fear just takes over me. During my exam time, I would study for up to about 12 hours a day, often missing meals because I was too focused on not failing and was too nervous about not trying hard enough and failing. It did get to a point where I fainted twice because I was studying so much I forgot to eat once.
I know I need to relax and chill...be mellow....but I just xan't help it.
Sometimes I fear that I'll turn into this person with no life whatsoever, or perhaps end up with some kind of mental problem because of the ridiculous amount of pressure I put upon myself in order to achieve what I want.