My periods last 5 days. My recent period was a day late and only lasted 2 days, skipped a day, and then it was just off and on bleeding on the fourth day, then nothing on the fifth day. I had really bad back pain, which I never get on my period. My fiance and I had sex a few days before my period started but he pulled out before he came, he always does. I've taken pregnancy tests and they've all come out negative. Is there any other reason why my period would be like that? 1. My period in January was 27-31. 2. My period for February was the 25, 26, and the 28. 3. We had unprotected sex February 13 and the 18, but he pulled out before he came. 4. I took a pregnancy test on the 1st and the 5th of this month.