Coconut oil fixed it for my daughter after one wash!!! Just rub it in, let it sit while you bathe him, wash it out and rinse with a fine baby comb....I had to wash again the next day cuz it was still greasy but the flakes went away!
My baby had that, when I bsthed him Id shampoo his hair with his soft brush and in like 2 bathes it came off. Also brush through his hair when it dry youll see all the flakes come out