Hi welcome to HCM... Your daughter having intolerance to milk that is dairy product so could have lactose intolerance..... So if she is having diarrhea from dairy product than they should be avoided .... While having diarrhea maintain hydration..... Meanwhile investigate her with ..... -USG abdomen -stool examination If chronic parasites infection is there treated with suitable drug like albendazole .... If stool shows pus cells than treatment for dysentery done by antibiotic like metronidazole .... If stool sticky , with mucous examined for lipid also ....and if with time problem not resolved than colonoscopy might needed and biopsy taken for histopathological examination... Take care ... Hope I have solved your concern...