James, the state of your tongue maybe an indication that you have a yeast overgrowth going on. NOt just oral, I mean your gut. THe coating on the tongue happens during candida or when a person is detoxing or getting die off from killing candida. So it can worsen initially as you improve your diet as the yeast starts to die.

Not sure if you are or not, but consider going on a candida diet to help this.