Exercise causing oxygenation drop

I had a bronchoscopy because after listening to my account of not feeling well (ie worse than with “just” MAC and BE, my pulmonologist performed one and had specimens anaylzed for bacteria/fungus. The results came back positive for pseudomonas aeruginosa. It’s not clear why I developed it although I did have surgery the previous May under anesthesia and the bronchitis, too, was under anaesthesia. Hospital settings are known to have this bacteria. So I was given the option of a drug like levaquin or a mebulizing treatment using tobramycin (TOBI). After researching both, I opted for TOBI. I was prescribed the 28 day twice a day regimen and stuck to it religiously every 12 hours. I knew I might need another treatment after a month off but it appears to have been zapped. Doing this was difficult. Lots of coughing and producing significant mucous from my lungs. I learned that this organism’s outer protective coating was vulnerable to 7% saline - in other words the saline weakens the pseu aer membrane and makes it more vulnerable to the antibiotic. I did not sleep well for the entire month and I did develop tinnitus but not severe a d it seems to be abating. I am continuing to nebulize with the 7% saline, huff coughing, etc. apparently MAC doesn’t “like” the saline nebulizing either. I do feel much better and I am hiking 3-4..5 miles 3 times a week and hope to bump that to 4 steadily. Easy does it, of course. I am 81 and have been a fan of physical exercise my entire life - used to be a trail runner but now hike instead.