Babies at that age need medication dosages adjusted very regularly so your baby may need the dose adjusted, even if not much weight gain some bubs require a higher dosage.

I am highly suspect of CMPI (cows milk protein intolerance) based on what you have written. A huge proportion of reflux babies have CMPI and then about half of them are also soy intolerant. I am a member and volunteer for RISA ( reflux infants support association) and they have lots of great info on the website and if you join as a member you have access to our private Facebook page, a library with lots of books about reflux and allergies, intolerances and gut issues, forums and more. My only regret is that I didn't job. Earlier in my children's reflux journey as I was told that babies grow out of it ( which most do by 12 months but my daughter is 4 and only recently off meds and my son is 2 and only just come off meds and probably needs to go back on them.