My periods are somewhat heavy but they are regular-30 day cycles- and luckily I never get cramps. I have been sexually active since age 13 and I am 34 and have never gotten pregnant so I assume I can't. My last period started Jan 23. I recently started medications for hypothyroid and my doctor thinks I may have PCOS even though it has been ruled out in the past. Anyways I have been having unprotected sex at least 3 times a week. 2 days ago during sex it seemed my period came but then it stopped. Yesterday I had cramps but no bleeding and today I had some bleeding just a few drops here and there. This has never happened before and I am so confused. I was tested for std's just 3 weeks ago and results came back ok. What could be causing this?