So yesterday was a pretty rough rehearsal... the drum line kept on asking the horn line to play certain songs over and over again to the point where i was ready to go home, and these are pretty tough songs (you know, quick march beats with not a single note below the third f). the drum major knows that as the lead i can only play some of these songs "x" amount of times before my lips are gone, and to add to this i had no back-up, AND i had a toothache. the problem came when towards the end of rehearsal i could not keep my lips together. i would actually feel the right edge of my upper lip slip out from being tucked inside my mouth whenever i tried to play a note past third a. naturally air follows the path of least resistance so once my muscles gave out my lungs emptied out into the atmosphere. this is the first time this happened... anyone ever experience this? is there something i can do to prevent this? Please help!!!