Pregnant?

I never thought I’d be one of the women asking this question because yknow who hasn’t taken sex Ed? However, I had this weird incident with my “period” at least I hope it was. I had my baby three months ago. My period is usually heavy in the beginning and then medium flow towards the end. I had unprotected sex with my boyfriend maybe a week before my period and it was a close call. I was on top and he pulled out and ejaculated. I got my period a week later. It was heavy for the first two days with small clotting and then I was spotting for the rest. The third day it was bright pink spotting and then the next few days it was brown. What could be the reason for this?