cradle cap

my son is 3 months & has cradle cap really bad. i only wash his hair once a week maybe not even that, i know when i give him a bath i dont wash his hair everytime. only when i see it get oily.. should i just not mess with it and let it go away on its own? my daughter had it but she had so much hair you couldn’t even see it.. any suggestions? im also gonna ask my dr what she recommends also