I don't sleep, it's my 3rd day without sleeping, i'm so nervous/can't concentrate or do anything, i also fainted yest with no reason, what's wrong with me?

Go see your doctor: Yes, i know, that's my standard answer, but it's near impossible for me to hazard a guess as to what's going on w/you w/o more detailed history, physical exam & diagnostic testing. That's why you need to go see your family doc who can start basic evaluation & refer you as appropriate. We worry about drugs (any otc supplements?), thyroid, anemia, dehydration, arrhythmia, bipolar, pregnancy, etc.

Two questions here.: The first concerns why you are not sleeping. This could be anxiety, stress, eating too late, having coffee too late or other things. The second concerns what effect sleep deprivation is having on your body and mind, and there's really nothing good here.