So i got my period 3 weeks postpartum. I missed my period the month of May, never took a pregnancy test. I recently got my period on the 3rd. Prior to that I had really bad cramps on and off. I went to the bathroom the other night and this fell out of me, as soon as it fell out my cramps stopped. Also I am on birth control. Could it be the lining of my uterus or something that was supposed to turn into a baby?