Hi, I've only ever had this once, and that was due to nerves at a gig. I was playing at a professional Jazz festival. Our Sax player was a pro (the rest of us weren't!) and she lived next door to the organiser of this festival, and got our group in as a 'local' band.
It was utterly terrifying, as we ended up playing mostly to the real artists or their relatives, as we were put on before most of the public arrived.
If nerves aren't your problem, then sorry, no, I don't know what to suggest.
Cheers