i was on contraceptive pill dece,ber to febuary, and got sick, so i took antibiotics. then after that, i had my first depo shot last march, i started taking diet pills (Chinese made) while im on depo, last april i started feeling feel sick and nauseated. spotting brown to light red for a month (april to may), tired and sleepy. cramps, lower abdomen and left side of my hip. i have taken 4 pregnancy test this may, and they all went negative. what is happening?