In my book it could be related to your age and your physics. You aren't as strong as you once were. I've had a couple of days when everything in my playing just broke down. I'm 61 so a bit younger than you, but I can feel the difference compared to when I was 25-30 in a lot of aspects, most not related to playing. My playing is acctually what's work best. I guess it's because I practice and still take care of it, but my body isn't as fast as it used to be and not as strong as before. I notice this a lot when I work in my garden. At 61 I can still play lead for hours and never feel pain or get worn out, but two times in about the five last years my emboushure just did not work. Lips didn't vibrate. Quite bad issue. What I did was to change to a slightly larger rim for a day and play less. I could feel the difference the very next day. My strength was back. Best thing could have been to rest the whole day but I didn't want to do that. I wanted to experiment and see if I could play and still repair myself. Yes, it worked, but that day when I returned to my smaller Bach 11C I only played for about an hour. I didn't play very well that day, but I don't know how many who really could have noticed if I had an audience, but next day, the third day I was back to normal again.
/Tom
