Rinsing your nipples with a vinegar and water solution (1 tablespoon vinegar to 1 cup water) after every feeding is helpful. Use a fresh cotton ball for each application and mix a new solution every day.

From La Leche League: After treatment for thrush begins, the symptoms may appear to get worse for a couple of days before improving. While the pain continues, offer your baby short, frequent feedings, beginning of the least painful side. Be sure to rinse your nipples and let them air dry after each feeding