baby Zantac, gerd reflux

My baby had been super fussy after feedings and spitting up a ton. His growth curve went from the 50th percentile to the 20th. Pediatrician decided we should try baby Zantac as he was showing signs of reflux. Omg. I have a totally different baby. He hasn't puked since the first dose. He's STARVING, basically has been eating non stop since yesterday when he started the medicine. I can't wait to get him caught up on his growth! So glad he's finally keeping his milk down. I breastfeed. Anyone else's baby on Zantac? How long did it take them to get back on track? We have a weight check in 2 weeks.