i was on depo Provera , andd i missed my 2nd shot but i qot it a week after , andd that following i qotten my period , and a month after i had sex , but 10 days after i had this light brownish bleeding but it stopped 3 days after , and ever since nov. of 2010 thru december i was losing weight now im gaining so much weight andd i have this ugly little brown line under my belly button to pelvic bown, i dont think it pregnancy be/c i took 3 test andd the 1st 2 were positive but the last one negative and i took the last one in a clinic! what is wrong with me ?