this is what we call Seborrheic dermatitis
that's bothering your child.
you should not be too worried about this condition as this is a self limiting condition that goes off on its own.
but in severe cases we can use some anti fungal creams or washes alone or with somke steroid
creams as has been prescribed to you.
so, i dont see a reason for you to be worried much about this if its not spreading, and wait for this to resolve on its own.
you can also use some mineral oil application on the lesions and wash them off with some mild shampoo or body wash the next day as this may work well in some cases.
hope you have benefited from my answer