Help!!! FTM here....

I'm 36+6 today. I'm a FTM & need your advice. From last 2 weeks My tummy becomes hard as a rock for 2 minutes and becomes normal again. This has been happening just twice daily.
From last 24 hrs it's more frequent. It is every 15 minutes now. When the tummy gets hard it's really painful & I feel as if my skin is going to peel apart. Baby is 50% engaged. No cervical check done so far. But the stiffness is only in the upper part of the tummy. I could feel the very lower part of my tummy being normal.
I called my midwife yday & today. She is saying if they are 5 minutes apart then to give a call back. I don't think they are bothering about the pain I'm going through!
No spotting. No bleeding. No water leake. I wasn't aware of losing my mucus plug either. Only mild cramps & mild backace. Less then my normal period cramps.
Wondering what is this?
Pls advice me whether I should go to L&D?
Is it a Practice contractions(BH) or is it gas or are they real contractions?
Thank you all.