Myles had some definite cramping and discomfort after his solutabs doses for the first two weeks. I was so discouraged because I was hoping Prevacid would turn things around and it only seemed to be making things worse. Fortunately I read here than some babies react to the aspertame or the lactose (or both) with cramps, but that this side effect often passes as the body adjusts to the medicaiton. I’m so glad I read that because I stuck it out and sure enough the cramps stopped in two weeks or less and Prevacid did turn things around for him. 
I hope your little sweetie adapts to the Prevacid and that it ultimately helps her as much as it helped my little guy.