1 year old rash

My 1 year old is taking antibiotics because she has a red throat and ears so she’s bearly on her 3rd day and she already has a diaper rash and the medicine is giving her a diaper rash and diarrhea is there anything she can take for diarrhea cause she’s does diarrhea every hour or 30 min that’s why she has a diaper rash and is there a good ointment for her diaper rash cause I’m using destin and it’s not helping ?