Not a singer/performer but this is also a concern for me if I am talking a in a crowd or have to speak up so people can hear me, it can bring on a cough. Frustrating. I've read that singing is very good for lung health so definitely keep at it if possible! Maybe use albuterol and an extra clearing before the event. Maybe even a puff of albuterol before performance? You might build it into your practice before the performance to see if it is helpful. Possibly avoid known mucus causing food for a day or so ahead? It'd be great to get a RT consult about this. Wishing you a cough-free performance and many years of performing ahead.