Rebecca, With the exception of coughing I know your story. The lack of sleep is wearing me down. Your summation, "I feel desperate, depressed and exhausted." For me it's spot on. I get low dosage CT scans every 6 months, a follow up to cancer and a lobectomy LUL in 2018. It's the problems that latter showed on the CT scans unrelated to cancer, MAC.
I'm 85, the idea to give up the fight, sit back and wait my time out looms over me.
There are no magic wands.
Don