Hello,
i'm sorry to hear about your daughter. I have constipation as well as CG and gluten free has helped a little bit, less refined sugar has also helped some. I haven't found a specific diet though that helps both. If her constipation isn't so sever try fiborous foods but I was told that because mine was more sever I should stay away from fiborous foods. i have been doing Pelvic floor physical therapy maybe some stretches or exercised would help. I hope she feels better. It's a tough situation but try to keep her positive and distracted it helps so much.