I had my period on Saturday October 6th, it was light on that day, then on Sunday it became heavier, it lasted until Wednesday. Usually I have really heavy periods. Now after my period is over, I m experiencing lower back pain , and some cramps . Last month, I got my period on the 10th of September, and had unprotected sex with my boyfriend on the 16th which was my last day of period, and on the 17th. What can the causes of these pains be? On a side note, I ve been on the OCP Yaz since last February. There isn t a possibility of being pregnant right? Since I had my period this month.