could be thrush, which is very common. Thrush is basically
yeast overgrowth, and people get it from many things including antibiotics, birth control pills, foods, etc... Yeast thrives on sugar, so try "laying low" on the sweets for now. You should definitely have a doctor check it out. If it is thrush, your doctor will give you an anti-fungal to take for a few days, and voila! A magic trick! Turning a white tongue pink again!