I just checked my saline spray that I used to use, and it does have benzalkonium chloride in it... Thanks for the tip. Luckily, I happened to have some "Simply Saline" on hand because it came packaged with it, though I never did much with it. I think I'll give it a whirl for a while here and see if it helps. I think there must be something to that "empty nose" syndrome you mentioned earlier; I hadn't thought about that.
I've definitely heard a lot about magnesium deficiency being a major factor in CFS. In fact, I just ran across a webpage that happened to mention how hyperventilation causes you to loose magnesium in the urine (http://www.immunesupport.com/library/showarticle.cfm?ID=2892 for anyone who is interested). Interesting...