Help...

I’m 27 weeks pregnant this Thursday, my belly has been rock solid all afternoon, and most of the day, I’ve tried doing a bit of walking, sitting down, and sitting on my exercise ball (which didn’t help as now I’ve got back pain!) I’ve heard of Braxton Hicks but read that it’s only now and again and not a frequent feeling! Literary feel like he’s stretching out my belly and sides feel stretched to the max 😬 anyone know what this could be and whether this is normal? First baby so i don’t have a clue 🤷🏻‍♀️