Baby eating less all of a sudden

My baby girl turns 5 months old in a couple of days. The past couple days she’s been eating less and she cries when I give her the bottle. It’s sooo hard to feed her all of a sudden and it’s frustrating me. Does anyone have any ideas what it could be from? She did have reflux and we switched formulas about a month ago, and she’s been doing much better on the new formula. Now all of a sudden she’s not taking the bottle. Is this teething thing maybe? I seriously can’t tell. shes only been acting fussy when I feed her so that makes me think it’s not a teething issue. Although maybe it hurts when the bottle touches her gums? Not sure tho😩 I will call her doc tomorrow. Just looking for input thanks .