Sex during pregnancy


Me and my boyfriend have been having sex the whole time during pregnancy, I’m 19 weeks, but I would be laying on my stomach, side, or back when I had an orgasm but today I was on top when I did and now I’m having like tight cramping right after and my stomach is very very hard. I’ve heard that it’s normal to have pain after an orgasm but I’m just wondering if anyone else has experienced this before.?