Not gaining weight/acid reflux

Brittany

My daughter is 2 months old. She’s 10lbs 7oz, she was 7lbs 7oz at birth. In 2 weeks she’s only gained 6oz. She was in the 58th percentile at birth and now she’s in the 21st percentile. She has terrible acid reflux. I feel terrible that she’s barely gaining anything, she spits up sometimes half of her bottle, or spits up barely any. I’m steady having to change her bib/outfit due to it. Is anyone else having this issue? I’d love some insight. She was gaining weight at first, slowly but still gained; but her acid reflux just got worse. She’s on Zantac right now to see if it will help. We’ve switched from parents choice, to gentlease, now we’re on soy. He said next stop is lactose formula, he’s giving her a month to see how she does, then we’ll be switching again.