HELP!!

Idk what happened but me and my SO were having sex and during the sex everything felt good and normal but the moment I got off of him I had severe cramps! I mean I have not ever had cramps this painful, I could not stand up or move because they hurt so bad. They lasted for 20 minutes and then eased up and now I'm just a little sore, but it was scary ladies. I'm afraid to have sex again for awhile so I'm going to hold off. I have no clue what could have caused it. I'm supposed to start in a few days but I've not had pre period cramps like that before. Any opinions or suggestions?? Should I go to the hospital?