Why is there a vinegar like smell coming out of my ?

A couple of weeks ago at a concert, I was performing and as I got on my knees to shout into the mic I got the whiff of a pungent vinegar like smell. I thought nobody else noticed, but they did and we had to cancel the concert because the smell was too strong. Thankfully no one noticed it was coming from my this time, but I don't know if I'll be so luck next time. How do I get rid of it? As I write this, I have a surgeons mask on to filter the smell. PLEASE HELP!