I developed a cough that wouldn't go away a couple oif years ago, and in the end the doctor decided it was "late onset Asthma", and prescribed me a couple of inhalers 0 Becotide to be taken morning and night, and Salbulin to be taken as and when needed. He said I'd need them from now on.

Seems to have solved the problem. What I mean is, it might be different medication or some kind of other treatment, such as breathing exercises, for you, but with Asthma there's a good chance that there is something that will sort it out.

And in the meantime you can concentrate on playing the music even if you can't sing the songs. Playing music always makes people feel better.