Like you I am blessed with allergies to just about anything. Several years ago (1983) I had a rynoplastie(SP?), nose job. They straightened my deviated septum and cleaned out and ground down one of my sinus.
That helped tremondously. I could breath better and my sinus infection every 3 months or so stopped compleatly for many years. The proceedure gave me better drainage, and so I did not get the infections as often.
I am now due for a tune-up and hope to have the other one done soon as it is starting to cause more problems.
I try not to dive with an infection or stoppage of anykind. I do medicate year round, and before a dive I use a breath-right strip and vicks vapo run all night the night before, then I apply a dose of Afrin 12 hour at least 4 hours before a dive, and another dose just before the dive. So far so good. But again, if I feel anytning but clear headed, I don't dive. The above is just a precaution.
I have never had a reverse blockage, but this is one of my greater concerns.
Check out getting a nose job. You will very likely be happy with the results.
Oh, and by the way, do NOT let them do it under a local. My mistake. I felt almost nothing, but the sound of that hammer and chisel inside my nose, un uh.... and the dreams after wards. Next time is knock me out doc. O course, they were chiseling as the last thing they did, right when things starting waking up. I told the doc I felt somthing, he said, its ok, I'm almost done. Easy for him to say. I also recommend pain killers when they tak out the packing from the nose. Now that hurt!!!
Just mho