My 1year old baby boys nappy rash is worsening from a rash to a red blotch from his anus up to his testicles. what could it be and how do i treat it?

DIAPER DERMATITIS: 1.Irritant contact: due 2 skin overhydration, maceration, long contact w/urine, feces. Red, scaly w/fissure, erosions, patchy; folds spared. #2. Candida/yeast: warm, moist occluded skin of diaper area help candida growth from stool. Red rash on perianal skin, folds, scrotum-, spreads. Rx: wash w/warm water, change diaper frequent, short period w/o it, use zinc oxide paste. See doc for candida tx.