Holy mother of god. CRAMPS.

I have begging for sex from my boyfriend for three days, and I finally got it tonight ☺️☺️☺️☺️☺️☺️☺️ (thank god any longer and I would’ve died) and he had me laid out ass in the air, laid on my back legs in the air and did fuck me pretty hard on some times, and after I felt the worst cramps, we have had VERY rough sex before and have done theS positions before and I never felt cramps, what does this mean? I’m also 3 days late on my period and I feel these crazy cramps? Help me please!