TD. You poor thing!

There are a few things to consider. Firstly, you really need to find out if it is thrush we are talking about. A lot of different infections/irritations can mimic thrush like symptoms. In the absense of discharge, there is a possibility that we are trying to treat a different thing altogether! Going to the doc for a swab is a great idea. That way you will know what is causing it. Thrush is caused by a fungus (usually candida). It can however be sometimes a different organism, so the dr needs to know in order to treat. Canesten won't treat all types of thrush.

Have you had your blood sugar tested? High sugar levels/diabetes will predispose to thrush. Avoid sugary food, white bread, flour products, wheat and drink heaps of water.

Overtreatment over such a long period could have lead to acid imbalance in the vagina. This predisposes you to catching thrush.
Avoid soaps, perfumed body washes etc in the v-jay-jay area.
Avoid taking baths. Quick showers with warm water to cleanse down-there is better. Dry thoroughly and only wear cotton underwear. avoid g-strings, nylons, stockings.
If you use panty-liners, change frequently.
Wipe front to back when going to the loo.

There is a product called Acijel which is a vaginal gel to restore the vaginal pH. I would highly recommend this ( available through your pharmacy).

Like the other girls have suggested, probiotics are great. These restore the good bacteria to your system which helps kill off any fungal growth. Inner health plus is a good product.

I would also suggest Ecovag vaginal pessaries to use overnight for 10 days (or more). this puts the good bacteria directly where it's needed.

Also, (very important) you should treat your partner at the same time. If you have thrush, he will also be infected and re-infect you, so you can't shake off the cycle. He can use Canesten/Daktarin cream on his boy bits.

HTH for now. GL at the doc's. You shouldn't have to put up with this for so long!