Red, shiny rash with yellow pus and crusting behind infant's ear Our 3 month old daughter developed a red rash behind both ears. The areas are shiny with yellow crusting. There is also an unpleasant odor along with the redness. The same rash is on her neck, armpit and behind her knees. I ve been meticulous about batheing and drying all skinfolds. Very concerned, esp. about rash behind her ears.