baby is up and down...

Does anybody else have this problem? During the day, my baby sits way up high under my boobs. Then at night, he gets way down low in my pelvis, right on top of my bladder. It's been this way for a couple of weeks, and is super irritating because I don't EVER have to pee during the day, but all night, every night, I'm up constantly since he wants to be so low. Anyone else notice this?