what could it be?

Marissa β€’ Marissa 23, Mommy to a 3 yr old named Kylie Jade ❀8mo old Karsyn Ryleigh πŸ’œ expecting baby boy 2/14/19. In love with their daddy 5-29-2010πŸ’

Im 24 weeks and my stomach keeps getting really hard/tight ever so often and it's super uncomfortable. What could it be? I never had anything like this with my first baby