burning tmi kinda?

Earlier I had sex with my boyfriend and I just got home and went pee and realized I had Just started my period..but when I started peeing it burned like hell fire and it hurts so bad even when I was done peeing...what the hell? What does it mean?
Extra information---
We didn't use a condom..
It was sorta rough sorta not but it's like we normally do but I've never had this happen