Hi Butterfly. What happens when you get chronic sinus infection is that a mass of infected mucus lodges in your sinus cavities. The mass becomes impenetrable by your body's microbial defenses, and the toxin from your defenses battling the outside of this infected mass irritates your sinuses.
In your upper sinuses, this mass blocks access to your olfactory nerves, and if you can't smell, your sense of taste is extremely diminished. (Yes, I have experienced that).
Surgery often removes the infected mucus mass, but often it doesn't get everything, and the remaining microbes grow back.
My invention, the Flip-Turn Sinus Flush, removes the infected mucus mass with hypotonic saline.
http://www.medhelp.org/user_journals/show/2322
The Flip-Turn Sinus Flush is mildly risky, because you have to bend over to do it, preferably in a shower, but you can also do it outside on soft ground, or you can kneel down and lean over a bathtub, or perhaps a plastic basin or tub, with the shower running for steam.
The major difference between the flip-turn and regular saline irrigation (such as the Neilmed Sinus Rinse, which is used by millions now) is it's highly improbable that you can squirt saline all the way up into your upper sinuses (where your smell nerves are) because of gravity. You have to get your head upside-down with saline in it to get the saltwater there, using gravity)
The flip-turn is even more risky, given your medical condition, but as you note, no smell is riskier than that.
I'd also recommend nettle leaf capsules, as the magnesium content may lessen any possible allergies that may have caused the sinuses to get infected in the first place, and there are no side-effects for nettle leaf.
Good luck.