babyrib,
I think 奶癬 should be irritated by milk, so is the rash around the mouth? How old is your baby?
My girl also got some rash over her face when she was 3-4 month-old. The senior said it was "濕毒" and used 金銀花褒水
to wash her face. I didn't use any medication for her but I
applied the aqueous cream and vaseline to her face frequently. It can prevent any irritant (saliva or milk) to her skin! The rash gone when she was around 5-month-old.