Need some immediate help. On my studies?

I'm a medical aspirant and had dropped a year in kota but couldn't make it through and the worst part was that my marks were very less though I'd studied a lot. I decided to drop a year again in my hometown but now I am unable to concentrate on my studies and I don't even feel like doing anything. I just feel like crying and most of the times I don't even know the reason. I don't even feel like attending the classes and when I do I feel trapped and feels like somebody is suffocating me. I'm not at all attentive in the class. I like being alone and I dislike talking to anyone. Any sort of noise(even people talking around me) gives me a headache. I have lost all my confidence and I've become a very pessimistic person. I've also been sleeping a lot. Earlier I was a cheerful, confident and bubbly girl. I hated crying and all but somewhere in this rat race I've lost myself. What shall I do so that I may concentrate on my studies? I would be highly obliged to you if you help me out.