My daughter is going through the same thing actually both of my daughters I grew out of it, but they have them prescribed the shampoo and stuff to use in the shower never medication and the itching and the flaking is getting very noticeable

Salicylic 3 % Shampoo. Treatments for "cradle cap" are also used, such as mineral oil. Applied for a couple hours prior to shampooing. Be careful which oils you use because you don't want to feed the yeast. Mineral oil, Jojoba and Squalane (not Squalene) are some I was told that do not feed it. When I was using olive oil, my head got so itchy. I guess it's a subjective experience but this is what I have found helpful.
Hope you find relief.

I read mineral oil like for baby’s cradle cap is effective. Couldn’t hurt to try prior to shampooing, I’d guess. You could read up and see if it’s something you’d try.