Two days in a row I have practiced badly. My vibrato is gone, replaced by nerves and tension. I make dumb mistakes and more serious ones. Not a good sign the week before a recital, not good two weeks before an orchestra concert.
Maybe this will help tomorrow at (orch) rehearsal: don't grimace or make a face if you fuck up or if it doesn't sound nice to your ear. Very likely no one can hear you, and even if they can hear you they aren't really listening to the viola anyway, so unless you make a huge loud bad noise, people will think you're grimacing because you're negative and bad-tempered, not because you heard some small fuckup that destroys your (misguided) ideal of perfection.