Cheney recommends EDTA nasal spray to break down biofilm in the sinuses. I believe he heard about this treatment from Richie Shoemaker. EDTA nasal spray is available from compounding pharmacies -- I got mine from Hopkinton Compounding Pharmacy in Massachusetts.
Although I had no problem using it, I know some of the more severely ill patients in Cheney's practice seemed to have histamine reactions to EDTA. He recommended that they deal with this by using EDTA intermittently rather than every day and taking antihistamines (Allegra, H2 blockers like Ranitidine, or Benadryl) before using the spray.
FWIW, I have had chronic sinusitis since a few months after coming down with CFS in 1998. I once saw an ENT who specializes in non-surgical treatment of sinusitis, who did sinus scopes and cultures -- and he found that I have about a dozen pathogenic bacteria and fungi growing in my sinuses, including e. coli, and that a number of these are completely drug resistant. So, even if biofilm is protecting these organisms, there is no antibiotic or antifungal that would eliminate them.
About 18 months ago -- after years of chronic hoarseness that seemed unrelated to sinusitis -- I went to see a specialist in voice problems, Jamie Kaufman in New York. She diagnosed me with "post-viral vagul neuropathy", which means I have an injured vagal nerve, so that the sphincters in my esophagus and throat, which are supposed to close after I eat to keep food in the stomach and out of esophagus, throat, and upper airways, no longer close normally after I eat. In addition, one side of my vocal cords is slightly paralyzed, which is why I am prone to hoarseness. As a result of this vagal neuropathy, undigested food and bacteria from the stomach and small intestine end up sloshing at night into my sinuses through the force of gravity. If I lay down too soon after eating a "normal" meal, especially one relatively heavy in carbohydrates, my sinusitis and CFS symptoms are inevitably worse the next morning.
Bottom line: what works best for my sinus problems and CFS is eating a paleo-like diet and avoiding eating 3-4 hours before going to bed. If I eat a regular meal with too much carbs and then go to sleep soon thereafter, I wake up with blocked nasal passages, sinus inflammation, and sometimes the start of a sinus infection. If, on the other hand, I eat a paleo-like meal for dinner and then eat no or very little food for 3-4 hours before going to bed, my sinuses inflammation lessens, usually in fairly short order. This has systemic benefits -- less brain fog, dizziness, fatigue, flu-like achiness. This approach to my evening diet is not a cure, but it does lessen symptoms quite a bit.
According to Kaufman, this type of vagal neuropathy is fairly common, not only among people with CFS/ME. She orders tests to arrive at this diagnosis, but my guess is that you will know you have it if the regimen I just described improves your sinus symptoms. And, like with me, it might have broader systemic benefits.