9 month old with reflux

I’m new to this but I have a 9 month old who has been diagnosed with reflux. My older child was also diagnosed and we had success with his meds. I’m having issues with the medicine for the 9 month old. He’s been taking prevacid and pedcid twice a day for about a week and a half and he’s not doing well. I know it takes a while for everything to kick in but does anyone have experience with this combination of meds? we give him 3.5 ml of prevacid half hour before breakfast at 8:30am and 1ml of pepcid right after he eats. and then do the same thing for his dinner at 6pm. he does ok one day and then terrible the next. has this happened to anyone else? where they have on and off days? does it eventually go away? i feel terrible for him and just want him to be comfortable. does anyone have better success with the prevacid/zantac combo? how long after a meal do you give the pepcid? sorry for this rambling message.