You mentioned something that is actually quite accurate.
The tongue can be used to diagnose your entire digestive tract, because it is made of the same tissue and of course connected.
A coated tongue means that your entire digestive tract, including bowels, is coated. The coating is toxins from partially digested foods that the rest of the body ahs been unable to handle. More toxin is created every day because you are not digesting your foods properly, thanks to a weak and congested liver, stressed pancrease, weak stomach.
You cannot blame candida, altho you certainly do and will have a candida overgrowth due to this problem, because candida overgowth is another symptom, not a cause. To take Nystatin or Diflucan is to treat the sympton, not the cause.
to treat the cause, you must:
Strengthen the liver, the main organ of the digestive system; Do this with liver flushes, liver-supporting herbs, supplements, especially pancreatic enzymes to ensure all your food is digested before making it too the colon. Undigested foods feed candida. You can read more about this at www.liverdoctor.com and www.sensiblehealth.com
return your body to a better PH balance by eating 40% veggies, 30% grains, 20% protein and 10% allowed fruits. NO dairy, no sugars, no junk. Since it's difficult to eat tons of veggies, supplement with a super-green food like Garden of Life's Perfect Food.
Thoroughly cleanse your bowels. Dr. Bernard Jensen
has a great book on cleaning your entire body thru bowel management. It's avalailable here on this site, or from amazon for very cheap. Restore friendly flora to your bowels, G of Life's Primal Defense worked the best for me.
Drink spicy teas such as Yogi Tea's Indian Spice. It is full of heating/carminative herbs that help the stomach to create gastric juices, such as cinnamon, cardomon, cloves.
H202 therapy can also be quite helpful as long as it's food-grade H202 and taken not only orally but also via enemas from time to time.