Hello again~ Oral thrush is one condition that may cause the tongue to appear white. Oral thrush is a fungal infection caused by the Candida yeast. Oral thrush causes patches to develop in the mouth and on the tongue. These patches usually have a white or off-white color and may have an unpleasant taste.
Also, White tongue can be the result of an overgrowth and swelling of the finger-like projections (papillae) on the surface of your tongue. The appearance of a white coating is caused by debris, bacteria and dead cells getting lodged between the enlarged and sometimes inflamed papillae.
There are many good links on the Internet to learn about Candida, it is a yeast over-growth, it can cause all kinds of trouble. Here is one of many sites that may help you: https://www.thompsons.co.nz/health-conditions/digestion/candida/
I would try to avoid all sugars and yeast as these are foods that the Candida loves to eat and grow in. Ask for a prescription for Nyastatin, this is an anti-fungal drug that is used to get rid of the growth. Also, taking a good, high potency pro-biotic would be beneficial, this helps to put "friendly bacteria back in your gut, Candida doesn't like that.
Also, start taking Caprylic acid, this is from Coconut oil, you can get the tablets at any health food store. It's a medium-chain fatty acid with potent antibacterial, anti-fungal, and anti-inflammatory properties. These properties make caprylic acid a helpful treatment for many conditions. It's used to treat yeast infections, skin conditions, digestive disorders, and high cholesterol.
Be sure to also drink plenty of water, this will help to flush the system out.