Gentian violet--you get it at your pharmacy. It worked for us, and better than prescription meds. My baby was about 3 mos , it is so, so, so messy, but I was so, so, so desperate and it really cleared it up. You drop it in his mouth, feed him and it deposits on your nipples. I was nervous about using it, but I researched it online and it is harmless. Just messy.
La Leche leaders recommend this for BFing moms w/ thrush, so I felt OK with it.