Its going on 4 months and im still sick?

where do i start omg i have been sick since i had sex last year in nov 2010 which gave me the conclusion of a std (scared to death) anyway i got tested for all STD ,HIV,&& whatever else ,,, so i got a pregnacy test which was negative and a blood test which was negative ,,, && a couple weeks later i went to a GY and she told me i was fine she ask me was i stressin which im not so now im taking these pills ZEGERID that treats heart burn for about two weeks ok mind you my syptoms are : naseua , back pains , i eat alot alot ,i feel weird things in my stomach , no headaches just tired and moody and weak like i can walk but i get tired after a while and i use to run track so i dont know whats wrong with me any suggestions :(