Contractions?

I’m curious if what I’m experiencing are contractions. I’m 36w + 2d, and I’ve had what I thought were Braxton Hicks for a while, just an overall tightening of my stomach with no pain. Yesterday I started getting what feels like an intense menstrual cramp in my lower pelvis and lower back simultaneously. The pain lasts for about 20 seconds, then fades. It isn’t happening in any pattern or anything, just randomly and not close together either. Are these early contractions or just more intense Braxton Hicks since they hurt? I see my OB on Thursday for my first cervical check.