I have suffered from nasal polyps and chronic sinusitis most of my life.
The polyps - I am not sure what these are. They seem to come and go, perhaps due to allergies, perhaps connected to body pH, I don't know. I have even had a surgical operation to remove a polyp only to have it return several months later. IMHO the polyps themselves are not fungal.
The polyps do however worsen the sinusitis. Usually, a polyp will block up one of my nostrils (it can switch sides, even in the same day) preventing my sinuses from draining. The sinuses get backed up and the sinus infection worsens. When it is really bad, this can result in a pounding headache, a sore throat, and bad breath. Although as a general rule, I don't like to take drugs, a good sinus decongestant (with psuedophedrine) works wonders.
It is possible I have candida. I have done cleanses and changed my diet and my health, digestive function, and energy levels have improved. However, the sinus infection (which could indeed be fungal) seems to be a constant companion.