I too have had similar experiences..a series of deep coughs that both clear my lungs and make anyone near me (except my wife) take 10 steps away...particularly in the worst days of COVID. Anyway, when I'm in a similar situation..not musical..but giving a talk or even socializing..I take a puff or two of albuterol and sometimes use an OTC cough suppressant DELSYM, and sometimes I use Mucinex (extended)--not a cough suppressant but it seems to work. Also, I try to keep my throat "lubricated by sucking on sugar free Ricola. Obviously, we are all trying to find our way with malady. Good luck and thanks for your concert at the senior center --it's a real mitzvah!