I have had 10 sinus infections this year alone. I have the sjogrens plus the severely low t-cells so high risk for infection.
I will tell you that when you get sick take the antibiotics because you will just get a worse infection. I will also tell you that I have lost the hearing completely in my right ear and I believe it is from flying with an ear infection even though I was on medication.
The dry mucus we have is not normal mucus so the bacteria are not killed off by the normal bacterial flora of the nose and sinuses like they used to be. Also, when we are dry our mucus membranes crack and bacteria are able to enter and cause infection.
It is good to irrigate your nasal passages with saline/salt mixture. A Neti pot or the squeeze bottle that they also make works really well and is an absolute necessity. I am surprised that your ENT didn't advise you to do the irrigations.
Be aware that when we have the sjogrens and get ear infections we have very unusual symptoms that are hard for us to describe and understand. Also, the symptoms are hard for the ENT to understand. I have had 4 tubes in my right ear in the past several years and probably will get another one next week.
Knowing what I know now I (myself) would not fly at all with an ear infection even if on the tail end of the antibiotics. The cabin pressure pushes the bacteria in strange places so that they sit and simmer and more infection comes later. I flew in May of 96 and had a plugged sinus and right ear in June and just figured it was from flying. In July I had the worse infection in chest and many times to the doctor. It took me another 3 times to get diagnosed with ear infection and pneumonia and then I had to fight like crazy to get to an ENT cause I knew something was wrong.
I was right---bad, bad ear infection with tube and more antibiotic. The hearing loss started soon after and went quite fast. In 2 years I was pretty much totally deaf. Not worth taking any chances after I learned what had transpired in my case. Good luck. If you can see a doctor close to you it might be good to go as you may need to have your eardrum lanced and a tube put in. That would make the flight a lot safer. Good luck. irish