Rough patches are often a sign of eczema or a heat-related rash. Keep the skin hydrated with fragrance-free, age-appropriate moisturizers like Aveeno or CeraVe. Avoid hot water during baths, which can dry out the skin, and keep the baby in loose, breathable clothing. If the rash persists, spreads, or looks raw, consult a dermatologist, as you may need a mild, doctor-prescribed topical cream to manage inflammation.