Some people on this forum claim to have had success with Xylitol (a natural Sugar which is supposed to actual kill candida rather than promote it - do a search on google or this site for details).
If you have candida in your mouth then you may have it in your sinuses. If this is the case people have been know to mix up a strong solution of xylitol and water, then sort of snort it up into the airways etc..
Might be worth a try. Like I say do a search on this site and find the info and see how you feel about it.
Other than that try gargling with grape seed extract...mak sure you dilute it as described on the bottle else it will burn your mouth for sure!!