I would think that a sinus infection can occur from multiple sources. As divers, we probably suffer sinus infections more so than the general public. My wife and I use our own gear and my wife came back from a long trip to the Philippines a few mounts ago with a very serious sinus infection. It effected her hearing and required antibiotics to get rid of most of it. A little still lingers. Best course of action is to see an ENT specialist as quickly as possible for treatment. I was fine and think the problem might have started with all of the time in airplanes.