My tongue went from having a white film on it to pink what could it be also extreme dry mouth !

Xerostomia or: Dry mouth and red tongue can be a sign of an underlying medical condition (e.g. Vitamin deficiency). Because most tongue problems are benign and treatable, the prognosis is generally very good. Depending on the cause of your symptoms, your health care provider can recommend appropriate treatment. Rec.: see your dentist or physician to find out why your mouth is dry.

White to pink: Could indicate Thrush or Erosive Lichen Planus. May also be allergic reaction to foods/meds/supplements. See Dentist and Physician for evaluation, treatment, or referral.