Post sex question...

So I had sex with my boyfriend he has a much more than above average size penis (9 inches 😳). Usually we don’t have any problems but today we finish and I had horrible cramps. My period is supposed to come soon but I typically don’t get cramps before. Why am I having cramps? We did use a condom and have not had sex without condoms.

Update: I got my period a couple days later. I was also very over heated and dehydrated. All is good now