This may be similar to when dogs have mange. Try shampoos like Nizoral, Denorex, or Head and Shoulders. Also look up blogs by Morgellons sufferers, they may be able to help you. Not "skeptic blogs".
I would try using some form of lice treatment for a month just to see if that helps.
It could also just be winter skin making you itchy. The black pieces could be dirt,dust, sand, or even hair follicles.
The white could be dandruff or sand.