First, my heart goes out to you and your daughter. I understand the frustration, embarrassment, anxiety and distress that you are experiencing. I have the same thing and am no expert, but maybe I can tell you what has worked for me and you may see something that can help your daughter. For GERD, I purchased a 7" high foam wedge from Amazon for sleeping and this has really helped stopped acid, food, etc. from traveling back through my esophagus into my throat. I eat early and less in the evening. I began eating a Mediterranean diet, began walking, and lost weight. This was very hard for me. 🙄 I also saw a dietitian and she gave me a list of foods to avoid to help with GERD and I am fairly serious about not having spicy food, processed foods, caffeine, chocolate, etc. The list is long, but there are many foods that aren't acidic. It has really helped!
IBS is a nightmare. I can't seem to get a handle on what is causing it. I'm about to try FODMAP. Google it. It's a food elimination system to see what's triggering the constipation, diarrhea, bloating, etc. I hope something here helps.
I feel like my IBS is under control. I’m following the FODMAP diet, taking the probiotics found in Kefir, Chobani yogurt, and taking 25 mg of Nortriptyline daily. If needed, on occasion, I also take Imodium.