A friend of mine on LJ and her kids got thrush, and I thought I remembered that they ate yogurt and used Gentian Violet (? something purple) to help combat it. Googling for "thrush yogurt" suggests to me that yogurt might be able to help, but probably on its own isn't enough to cure thrush, and as long as you avoid sugar, wouldn't hurt. I believe that the idea is that the live yeast from the yogurt displaces the yeast that causes thrush. Hm, googling for "thrush violet" pulls up some concerns about cancer.