Irritable uterus anyone?

Apparently my uterus is pissed? lol I’m term now, 39 weeks, and I’ve been having this hardening of my belly where it gets as hard as a basketball and really uncomfortable, but it doesn’t go away in a couple minutes! It can last like 20-30min at a time. I thought they were Braxton, but my midwife said it has to be irritable uterus if they are lasting that long. anyone else experience this? maybe fact that I have a breech baby has something to do with it.