I noticed that you wrote your daughter only eats fatty foods lately. That may be a contributor to her loose stools. Fatty greasy food definitely causes my stomach to be upset. Mabe you can have her eat a little healthier to see if it makes a difference. I know it's hard but if that's all there is to eat then she'll eat it.
I know antibiotics can cause loose stools and you said she is taking Tobi and zithromax.
Prilosec can also cause loose stool problems.
If it were me I would stop taking anything that isn't absolutely necessary, and then gradually start introducing the other supplements back into my diet to try to identify the problem.
Hope this helps