Belly keeps getting tight?

Hey ladies,

I’m 20 weeks, and I’m noticing that when I’m doing a lot, my belly gets SUPER tight and feels weird.

For example, walking down to my basement, taking laundry out of the top load washing machine and putting into the dryer this evening, my belly was feeling very weird and tight.

Does anyone know what this could be??

Second baby, but I don’t ever remember feeling this with my first.