it's when a baby's scalp produces too much oil and occasionally can make hair fall out from scratching so much since it can cause their head to be really itchy. it can usually be identified by yellowy patches of dry/oily skin that can flake off just like dandruff

what is that @newmommy090715

4 months is usually about the time your body and the babies body catches up with the Trauma of birth. so it's completely normal for his hair and alot of your hair to start falling off.

could also possibly be cradle cap

it's normal it kind of rubs off while they sleep and if he runs his head against anything plus he probably likes to touch his hair but if you feel like it's something beyond that call your his doctor and just ask