Have they considered inflammation or a reactive airway component with your CF? If your airways are inflamed, your PFT's are usually affected. Once that is treated with steroids of some sorts and nebs or meds, improvement is seen if that is indeed the problem (or part of it). I mentioned synergy testing previously, again, I think that would be very useful in your case to find the absolute best IV concoction to treat your resistant bugs.. Hopefully your PFT's recover....perhaps going to columbia would be a good thing as there would be other minds/brains on your case. I am sure that they could figure something out before something like a transplant is done/considered..
Hang in there, thinking of you
Jenn 40 w/CF