okay I got another problem. when I have to "go" my tummy likes to hurt but I only pee a little.. and…

okay I got another problem. when I have to "go" my tummy likes to hurt but I only pee a little.. and this is through out the day of course... but it's like when I nap or even sleep through the night I wake up and feel like I'm releasing Niagara Falls. is he sitting on something constricting my flow or is this happening with everyone and it's just a prego thing?