Hi thanks for contacting HCM... Here according to history you are having diarrhea .... So because of frequent bowel movements there is irritation there ...... So yes can apply any moisturize if needed.... You are using vaselin that can be used.... Second here you have to treat diarrhea.... Maintain hydration with lots of water and take ORS also added in water.... Stool examination done ....If showing pus cells or you have complaint of fever and abdominal pain then antibiotic needs to be given.... If stool shows ameba like infection then metronidazole given... Hope your concern solved... Consult physician for this.... Take care ....