Skin rash for 21 month old infant?

Several, no many... Eczema, psoriasis, keratosis pilaris, fungal infection: these are a few of the many! See your pediatrician or go to a dermatologist!
Infantile eczema. Infantile eczema (atopic dermatitis) most common rash in about 10% to15% of children. With red, crusty patches. Dry skin contributes to worsening. Immune system reaction triggered by certain soaps, creams, allergies, and detergents, and may worsen with stress, heat, and sweat. Therapy includes moisturizing creams, luke warm quick baths, non irritant soaps, sometimes topical steroids if severe. See dr.
Many possibilities. A skin rash in an infant can be due numerous reasons. If the rash is associated with other symptoms such as fever, diarrhea or lesions in the mouth, then it could even represent potentially serious infections that need treament. See your pediatrician or a dermatologist to evaluate the rash.