Joey's breeder told me that the number one reason for white flakes is not rinsing enough after shampooing. Rinse rinse rinse, and when you think you've done plenty, rinse some more. I do another minute after I think I'm done, and I set the timer. I warm the towel in the microwave during this time. Also, a good cream rinse/conditioner is important, as you are conditioning the skin as well as the coat. She recommended Bio-groom shampoos and conditioners, and if you email the company they will give you free samples.
Bio-Groom - Exceptional Pet Care Products for Over 30 Years I feed Joey RC, and he has no flakey skin, but my little foster who eats Wellness has flaky skin, so I’m starting to use the shampoo and conditioner on him, and I’ll see if it helps. It's actually much easier to keep skin healthy than it is to fix, so it might take some time.