Pregnant & sex

I always have sex with my husband & it’s not uncomfortable during my pregnancy but tonight after we were done, I got a tight feeling in my lower stomach & I felt as if I had to push very hard & go pee but nothing happened. I had a really bad pain in my lower stomach. He wasn’t being rough with me.

I’m curious if anybody else experienced anything like this during sex while pregnant? I am 29 weeks by the way. It worried me because my first son was born at 32 unexpectedly.