Ugh. Thrush. We have it too. It's been almost 5 months now. We've tried everything: nystatin, diflucan, gentian violet, GSE (grapefruit seed extract), vinegar, and acidophilus. Also, I cut out all sugar from my diet. The oral nystatin did nothing except make the babies sick, although the nystatin ointment has been helpful for the yeasty diaper rash. The diflucan worked for me, but then the babies would just reinfect me when I got done taking it. The gentian violet worked to get the thrush out of the babies' mouths, but seems to only work temporarily for my breasts. GSE did nothing so far as I could see. We wash all of our clothes (and everything else) in vinegar and hope that it is killing the yeast. It never worked on my breasts. Acidophilus has been the best. It keeps the thrush at bay to the extent that I only feel a little burning now and then. The boys' mouths are now clear, and all that lingers on them is a bit of diaper rash. I take a few capsules of really instense acidophilus with bifidus (that's important) three or four times a day. It is expensive, though.
If I were you I would try the gentian violet, and also take acidophilus. I know that a lot of people have success with GV. You should know that there is an Australian study that links GV to cancer of the mouth. Most of what I've read and heard seems to dispute the danger of it, but you should do your own research before trying it.
Good luck! Thrush is horrible. I almost quit breastfeeding a few times when the pain got really bad. I'm so glad I didn't! Actually, weaning does not get rid of thrush, so there is no reason to wean!
Check out the bfing forum for more ideas. The thread is called "HELP! I can't believe we have thrush!" Or something like that.