Poor you and what a silly doctor!! It might not even be thrush; it might be a staph infection instead, in which case antibiotics and an antibiotic/antifungal ointment will be what you need (mupirocin is the ointment my doctor - a breastfeeding specialist - recommends).
I'd tried *everything* to get rid of what I thought was thrush (from when my baby was about 9 months till now, when he's 16.5 months), including several courses of diflucan (including crying down the phone to the doctor on weekend duty who refused to prescribe anything because I was breastfeeding! Doh! I needed help *because I was breastfeeding*!!). Then I finally made it to a lactation specialist doctor and her awesome crew of nurses and consultants, who immediately diagnosed an infection.
They should look up close at the nipples with an otoscope to see what's up. The symptoms aren't so different from thrush - painful nipples (during and after feeding), red and a little crusty sometimes (ick), and tending to be very dry between feeds; also sometimes pain that radiates back up into the breasts (this is usually referred pain from damaged nerves in the nipple, apparently). It can be on one side or both.
Infected nipples are more easily traumatised, too, so they are susceptible to tiny cracks and can thus take a long time to heal properly. The sooner you get onto it the better! For me, antibiotics kicked the infection itself, but the accumulated nipple trauma was so bad that I had to take several days' break from active nursing to get any real relief from the pain. It still hurts, even though there's no active infection.
Apologies for the long lecture - I just wanted to share the knowledge, just in case! And even if what you have is in fact thrush, maybe this info will help someone else who finds their way to this thread.
Is there a breastfeeding resources group in your area that might have more up to date knowledge on the subject of both thrush and nipple/breast infections?
Best of luck, hang in there, and I don't blame you if you never visit that ignorant doctor again!