Are you on the pill cos that can have bad effect on thrush problems.
I recently stopped taking the combined pill cos i discovered after a year of having the damn infection, it was the pill that was agrevating it. Went to the doctor (who was absoulutely gorgeous, made it all the more better and embarrasing at the same time) to get the injection instead and he said that there is now a mini pill that is basically the same as the injection and now doesnt have all the problems mini pills used to have - 99.9% effective now.
If you are on the pill, try stopping it for a month and see how that goes. If it works then try to get a prescription for Cerazette which is the one i am soon to start. Good luck with the blighters, i know your pain!!!