Hello. I'm Sam. Last December 31 I Had My Last

Hello. I'm Sam. Last December 31 I had my last normal period. Then I had unprotected sex on January 11, then on january 17-20 I had spotting when I wiped. I thought I was pregnant but I got my period February 1. Then on feb. 29 I got a little pinkish blood so I thought it was my period but after a couple of hours I had brown discharge for 2 days, then stopped. The next day I had a little blood again. Then stopped. Then will continue the next day. It stops and starts for 7 days already. Feb 29 to March 6. What's the problem? I don't take any pills. Pregnancy test negative.