Hi Njellibelli,
there are 2 things that come to mind.
The first is rumination disorder. Some doctors like to do a study like a bravo ph to find out exactly when regurgitation is happening but you don't have to if the history is consistent with the diagnosis. Is it at night while she is sleeping? for example.
Therapy is awareness and breathing exercises. Medicines usually don't help.
The 2nd thing that comes to mind is quiet common in peds GI, which is constipation. Even when kids stool daily, soft/hard or even diarrhea. It is not uncommon to find kids to have a large amount of stool in the transverse. It can be hard to diagnose because it won't be obvious on physical exam so many times the best way to diagnose is by a ped gi specialist looking at a KUB.
Therapy is a flush out, or 2 or 3 until the transverse colon clears out.
thank you and we hope to see you around,
Team @ MLTA