FODMAP diet will probably fix her gut along with a well rounded probiotic with at least 16 strains. Avoid ultra processed, sugary, salty, fatty. No sodas or juices. Theres a list of foods okay to eat and foods to avoid for people who find the FODMAP diet resolves their issues. I had to keep it on hand for 2 years. Its strict, but whatever it takes to get out of the bathroom right? A Gastroenterologist suggested it to me over 10 years ago. It works awesome, but sucks when dining with others. It is what it is though and beats the need to take loads of immodium, gas X, heartburn and anti nausea meds all day every day. I got to where I just don't care what people think about my culinary needs anymore. I hope your daughter isn't very young, really stinks for young people, especially girls, the stigma is tough to deal with, not to mention never getting invited to anything involving food sharing.