Hello how are you? I'm so sorry to hear that your great niece is having digestive problems. I went through the same issue when I was a baby. It started a few days after I came home. My stomach couldn't tolerate any type of formula and my mom had made the choice not to breastfeed. They didn't know if it was because I was born via c-section or what truly caused the issue. They ruled it out as me being lactose intolerant. Maybe Lily's lactose intolerant. Best of luck in finding what's truly wrong