I have been taking medroxyprogesterone for five months and my period has been regular each month. I always wait 24 hours to have sex though. The past two months, I would stop my period, and wait the 24 hours. However, I would spot for two days following sex (just that one time, not the rest of the month). This month I only spotted, waited 24 hours and then had sex. I started bleeding shortly after. What could be wrong?