Sex/bleeding/ just started birth control

I was put on 10mil medroxyprogestrine for 5 days started 7/27 to induced a late period. I got my period on 8/6 and was told that I didn't ovulate. The morning of 8/15 I started to get brown blood then midday it stopped completely. I thought finally the longest cycle of my life was over lol. So, thinking it was over I had sex with my boyfriend on the evening of 8/15. First session we had a condom on and I started bleeding lightly, we finished and thought maybe he was a bit rough. Eventually the bleeding slowed up and we had a 2nd session. in the heat of the moment ended up having unprotected sex. He ejaculated inside of me and during sex I started bleeding again. After sex my uterus had some painful contractions and the bleeding became heavier. To the point where when I urinated I had small clots and my urine was bloody. still bleeding lightly yesterday until about 3pm. When does ovulation happen? will I ovulate? I started birth control yesterday for the first time. Never had a scare before. Why did I bleed like that? Should I worry about pregnancy? I don't know what to expect or do. Please Help