The belly is constantly hardening for 3 hours, probably 10 times over,…

The belly is constantly hardening for 3 hours, probably 10 times over, but not more than that. There's no strong pain though. Is this normal? By the way, I even passed my ultrasound on December 22nd, but I still haven't given birth. And I can't sleep at night because I can't breathe easily, it's like a stone in my belly, like that. Has anyone experienced this too?