3 month old struggling with bottle...

Anyone else’s 3 month old all of a sudden struggling with the bottle?? I stopped breastfeeding a little over a month ago because she was pulling off and crying after about 3 minutes. I’ve been bottle feeding her both breast milk during the day and formula at night. She used to take 4.5 oz per feeding perfectly and now she struggles to finish 2... she’s also all of a sudden falling asleep in the middle of her night feeds... those used to be the easiest feeds!

Doctor says she has reflux but we’re on the second medicine (tried ranitidine first and now on Nexium) and I don’t see much of a difference... so I’m not convinced. She is otherwise such a happy and calm baby!!

Anyone else going through this with possible answers?? I’m so stressed and just want to help my baby!!