So you look into the mirror at your tongue, (or you are looking at the tongue of your child) and you notice that it seems to look patchy. Some parts are a certain color and others are another color.
What is wrong with you??? What is going on is called Geographic Tongue.
It is really nothing to worry about. It will come and go. It will move around. That patches will get more and less intense. When things flare up your tongue may be more sensitive to acidic foods (tomatoes, lemons, etc.)
There are no known treatments but people say that several things have helped them in the past. People note that sucking on mint leaves, steroids, and antihistamines have all helped to alleviate flareups.
Take home here is that there is not much to be concerned about death is not nearing (at least from your tongue).