Sue, you have just written my own recent experience. I got lax with the nebbing of 7% saline and took a break from doing it. Bad idea! I developed a cough because I had contracted aspergillus infection, lower O2 levels, they would drop scary low when I walked, and had zero energy. I went back on my tobramycin 3 week ago and nebbing my saline religiously. Cough is gone, oxygen levels back up, energy levels climbing. I have learned my lesson to not let my guard down again.