Early this year I had a bug, trouble breathing, doctor gave me inhaler. It was brill, I used it for a bit, then found I didn't need it anymore.
Just recovered from chesty/flu/throat bug. And I'm struggling again. If I inhale some cig smoke, cheap perfume, air freshener, then it feels like my lungs have filled up with porridge and a compression band is round my chest.
Found old inhaler, a puff or two and the symptoms go away.
I did some digging on the weekend, and according to some research, once you have COPD, you have it for life.