Diaper rash is a common form of inflamed skin (dermatitis) that appears as a patchwork of bright red skin on your baby’s bottom. Rashes from irritants can get a secondary infection with yeast. Yeast infections are bright red. They can be raw and weepy. Diaper rash is a common condition that can make a baby’s skin sore, red, scaly, and tender. Most cases will clear up with simple changes in diapering. Most diaper rash .