If she hasn't had a bowel movement in a few days, it could be constipation. I would suggest she visit her doctor. I had a friend who's baby was v*ing due to constipation and he had to get on medication, she may need the same. It doesn't sound like a bug, though it could be a mild one. I'd think it would have started with the v*ing though, or that there would be d* along with it in the last few days. Again, I would take her in to have a professional opinion, constipation in littles isn't something to mess around with.