There's some mixed results for witch hazel in the Seborrheic Dermatitis community. If you haven't already, I recommend reading up on Borax. It is actually used by doctors for treating vaginal yeast infections and has a better reputation in general for its antifungal and antiseptic properties and its used in a wide variety of applications. It has an overall bad reputation in the medical world however because of the concern for causing birth defects, however, this is only when consumed at very high levels. In fact, borax is less toxic than salt, which has similar birth-defect causing effects when consumed at out-of-this world proportions. All it is a form of Boron, which is actually quite an important mineral for optimal human health.
I'll keep you updated with the ketoconozole/borax treatment.