You may want to check out the research published in 1999 by Dr. Hirohito Kita, M.D., a Mayo Clinic researcher. He stated that 96% of sinusitis is due to a fungal infection. Clinical Mycology is not taught as a class in medical school so most physicians do not know how to treat these infections.
My mother had severe headaches from sinusitis because of her supplemental oxygen that she needed 24/7. The doctor presdribed antibiotics which did nothing. I tried Tylenol, Advil and aspirin at different times which also did nothing.
I researched fungal infections and found olive leaf extract nasal spray. I got some, not thinking it would do anything since the medications provided no relief but amazingly, my mother's headaches were gone in less than 15 minutes.
Prior to that find, her headaches lasted all day and sometimes into the next. I also found when reading a Clinical Mycology text that antibiotics "ensure the chronicity of fungal infections."
After that I continued researching and found a host of other physicians that had found methods of curing illnesses realizing the drugs do not do anything but mask symptoms.
I challenged my mother's doctors to name a drug that cured something and they could not name one.
Imagine there is a pathogen introduced into the lungs by smoking that proliferates causing your lungs to distend and eventually crowd the stomach. Starving this pathogen was one of the first things I did using a diet used by a NYC physician in his 8 step cure for asthma and also used in cancer research by researchers at University of Nevada School of Medicine under the direction of Dr. Kenneth Hunter.
This stuff works. It just doesn't sell thousands of dollars worth of drugs so you will probably never hear about it.
The best advice I can give is that you, 1) work with your doctor to make sure that you are receiving optimum therapy for the chronic sinusitis and, 2) Be meticulous in cleansing your CPAP tubing and adhere to recommendations regarding filter replacement, on a regular basis. Give special attention to the humidifier, as it can be any especially effective breeding ground for bacteria, fungi and other infectious agents. Finally, latex is a not uncommon allergen. Make sure it is not used in any part of your system.
Good luck