Suggest Remedies For Soreness And Redness In Anus Due To Diarrhea

my 2 1/2 year old daughter has had diarrhea for 2 days. Her private areas are red & blistered from the acidic stools. (she is still wearing diapers so it spreads out until we realize she needs changed.) What can I do to relieve her pain? she doesn't want to sit anywhere, including her car seat, b/c of the pain which is a problem.