So my baby is 4 months old, since he was born I've been giving him a combination of formula and breast milk. Not mixed. I've recently been transitioning him to just formula and he has started to completely refuse to take bottles. He only wants the breast at this point which is really concerning. I tried changing bottles and nipples. I've tried to mix formula and breastmilk and I've tried just expressed breastmilk and he will not take it. I've tried stretching out his feeding times and nothing. Today I got him new formula and he wouldn't take that either. I'm not sure what the issue is.. the pediatrician seems to think it's normal..

He's teething and has reflux that he's on medication for.

Any thoughts?