Cradle cap

Brittany👨‍👩‍👦‍👦☕️ • 28 yr old Boymom of two wonderful boys, Blaine and August. Currently pregnant with #3! Due December 2016 😍
Ok so my son is 4 and it looks like he still has cradle cap on his head. I can get it off with oil and a fine toothed comb but it keeps coming back!!! I don't know if it's CC or if it's something else. We wash his hair every night...it's just so weird! Anyone have any idea what it is and how I can get it to go away and stay away?!