My youngest had cradle cap as a baby and nothing I tried would get rid of it.  One day I was feeding him and reading my book at the same time (with three litle ones I had to snathcn every available minute).  I suddenly realised the cat was sitting on the arm of the chair and licking the baby's head.  I pushed him away then realised that a large patch of scalp was clear.  Carried on reading and pretended I hadn't notice the cast return.  By the time the feed was over, David had no cradle cap and it never returned.  I may have forgotten to tell the health visitor how I got rid of it.