side effects of prevacid?

Hello all. I tried to find this somewhere but no luck and my daughter doesn’t give me much time. Are there prevacid side effects? My 4 week old is on a low dose (7 mg per day) in the compound form and what I thought was constipation turns out to be watery stools. I don’t think it’s her formula because she’s been on Gentlease for a week and no problems until now. Could it be the prevacid? She’s also been on rice cereal in bottles so you would think she would be constipated. She didn’t go for two days and now it’s like water- you can tell her tummy hurts as she cries when she passes gas and pushes to “go.”