Bleeding after sex- HELP

I was on my period from the 25-29. Went away everything good. I had unprotected sex on NYE and my boyfriend finished off inside me. I am now bleeding but I don't know why, if it's from my period or what??? I need help PLEASEEEE
Side note, I lost my virginity about 5 years ago. I've had sex numerous times since then and never really had any problems that were out of the ordinary, no cause for concern. So it's not because it was my first time or anything