I Have White Patch In My Tongue For About 3

I have white patch in my tongue for about 3 month and it's some day little goes out and some day it's come out again and this alaways change place, some day 1 side and some day another side of tongue, it's not burning and not paining, but when I mouth breathtaking my tongue gets dry and discomfort me, and when air goes into mouth my tongue start dry and very discomfort me, plz help me give a ayurvedic or any other medicine so that it's goes out for lifetime