M. Sickness gone but waves of nausea?

19w3d. Morning sickness ended, thank god, with the first trimester but once in a while, I get hit with waves of nausea. I know light headedness is normal at this point but sometimes I'm sitting down when these hit. Not concerned or anything (I tend to get nauseated when im hungry. my stomach has never been one of the tough guys lol) but curious if anyone else gets this??