I havn't read all the links but I used to get a really bad itchy scalp that turned out to be triggered by eating peppers (capsicums) once I stopped these my scalp cleared up so maybe it could be food related. Also if it is food related this could point to a problem in the gut how is your digestion? maybe some raw milk kefir would help as it will nourish your skin and help with any potential problems in your gut.