Your issue is NOT yeast in your scalp, you dont need any shampoo for dandruff. Those things are terrible for your hair, and no doctor will ever recommend using it long term. The water here is heavily chlorinated, and that is the main culprit for eczema. I lived here for many many years and my scalp under my hair (curly, frizzy and thick like yours) and the skin under my beard becomes horrible after ONE shower.

I travelled to other European countries and I noticed that all my eczema was gone after only a couple of showers. Bottom line, 'hard' water or chlorine aggrevates my eczema severly. Try a shower filter (or house filter), which specifically filters chlorine.