Cradle cap is a common scalp problem that appears as yellow scaly patches on your child's scalp. If cradle cap is mild it usually disappears on its own within a few months.
If less mild, you can use mineral oil or baby oil on your child's scalp prior to the bath. Rub the oil into your baby's scalp, allow it to stay on the scalp for 10 minutes, then rub with a soft toothbrush and then wash the oil out with a baby shampoo.