C.K.
Both my girls had an ugly dermatitis on their scalp. Great big hunks of dead skin was just coming off in sheets. It looked gross and they said it was itchy. I used all the OTC dandruff shampoos recommended by their pediatrician, but none of them worked.
Then, I took them to get a hair cut at Cool Cuts for Kids and they sold me a bottle of Tea Tree shampoo by Paul Mitchell. In just two shampoos, the ugly flakes were gone. I use it on them once or twice a week and the problem has never returned. I gave a bottle to my mother who has bad psoriasis(sp?) and it has helped her as well.
Try it! Just remember it's not a "no tears" shampoo so make sure she keeps her eyes closed when you rinse.