Painful

Me and my boyfriend were watching porn together while I gave him a handjob because my period started. Things escalated quickly and he wanted to have sex. I told him I had never had sex on my period and he promised to be gentle. Anyways I made him wear a condom and put a towel down just in case. It was great but slightly painful at times. Well we finished and the pain is worse and it won’t go away. Did that happen to anyone else? Is it like an expected thing?