Your doctors are most likely correct, but if antibiotics don't work, there's nothing they can do. I developed the Flip Turn Sinus Flush, which gets rid of all sinus infections, but it requires that you bend over in a shower, which is risky, especially for anyone over 50, but you could also do it outside in the grass, wearing swimwear. Of course, I'm over 50 too, and I will still do it, just like I do everyting I used to do when I was younger, just slower and more cautiously.
http://www.medhelp.org/user_journals/show/2322