The first thing to check is: dental issues. This could be the primary source of all the other problems.
As for the other reasons for the "white tongue syndrome" as we'll call it, is this; The yeast, or parasites or in some cases viruses-have the ability to make chemicals which inhibit [f#$#$#@k-up] your saliva glands from making certain juices that keep the regular bacteria living in your tongue from having too many babies. This causes them to have big parties on your tongue, and when not enough air gets in there, like at night when yer sleeping, they really start to have fun! Shroom