Hi Your child seems to be having atopic dermatitis. This is a condition skin condition which worsens with weather conditions. So make sure to use a mild ph balanced wash for bath. Use lukewarm water and very short bath time. No bubble bath or bodywash which have perfume should be used. As soon as the child is out if bath use a thick moisturiser and reapply moisturiser often. Use only cotton clothes. Avoid washing baby's clothes in detail. Use a mild detergents instead. You may need to get a consultation with a dermatologist who can examine and recommend a mild steroid cream or oral antibiotics or anti itching syps. As this condition may take some more years to resolve these have to become a regular habit. However usually as he grows up the skin will also improve