http://thyroid.about.com/cs/publicawareness/l/bloprahletters.htm
This may help.
My hairdresser told me that dandruff shampoo was making my flakes much worse. I switched to Neutrogena moisturizing shampoo and conditioner and my scalp has been salvaged as well as my hair.
I still occasionally have flakes but they are few an far between.
Best Wishes~