I know this is a really old one but I had to respong to it. You know Doctors around here (Wyoming) hardly recognize yeast as a problem in children. I have an 8 year old son who had so much trouble with thrush as a baby. I wanted to cry! It made him very fussy as well.
I read a book called "The Yeast Connection in Women". This book does not only touch on Women and yeast, it tells about all people and yeast. When we take atibiotics it kills our good bacteria. When we do not have alot of good bacteria yeast is allowed to grow in our body. In babies it grows in the mouth because it is very wet and warm and also because of the milk. Yeast grows in a warm environment and is fed by starchy things or sweets, including milk or formula.
We tried the Gentian Violet, Diflucan, the white mouth rinse, all that stuff. What a battle! If you get a chance and find the book it will tell you what to do, if you can find a Doctor that supports the theories. My son is still prone to sores in his mouth and yeast infections. He is big enough now that I can give him supliments from the health food store called "Yeast Cleanse". I wish that Doctors would recognize this around here because in South Dakota I had such a wonderful Doctor that helped me so much. My son was prescribed 11 days of Diflucan. One dose every other day. It was liquid as he was really young at the time. We did this three times and finally we were without thrush. I also gave him the powdered baby Acidophilus from the health food store. For Mommy, yogurt, no sugar, bread or anything sweet. I pretty much at vegetables for three months. It was great for my figure!
Make sure if you have a pacifier you wash it frequently. Use a cool rag not a warm one to rinse your nipples. You can actually pass this back and forth between you and your child if you are not carefull. You can also give your child cool or cold milk. That will slow down the growth of the yeast in her mouth. We also were told to rinse the little mouth with water after each feeding.
I know this is so long ago but if you have not had results I feel for you. Thrush is so misserable for both your baby and you.