Ok well I suggest you try a Neti-pot with Grapefruit-Seed-Extract extract. A lot of people have been cured here using that. The fact that you had poor sinus' for years is very relevant. Is your odor worse after dairy or sugars? Do you have bad breath?
You could have a sinus infection or harboring bacteria in your sinus that causes the odor.
Before buying the neti-pot try the candida diet. This is a diet completely void of sugar. If you have a positive reaction from this diet and the odor reduces or deminishes you know it's bacterial and how to take the next step for further treatment.