Hating bottles

She has been strictly bottle fed breast milk since birth she’s 4 1/2 months now, and the past couple weeks she has horrible feeds she fights the bottle when it’s in her mouth and like grunts pushing it away and we don’t know why she’s doing this?? She’s been to a doctor they checked her mouth and throat and nothing in there and then they completely ignored our questions about why she hates her bottle now? She has reflux but is up to date on her medicine. Anyone knows what it might be?? Some feeds are great and some she does all that even though she’s hungry