The last several days when I practice, I find that within 10-15 minutes, my middle upper lip is sore and also feels fat and numb. Anything over G above the staff has become pretty hit-or-miss.
Here are 3 things I can think of that I've changed in recent weeks:
1. I started using ChopSaver instead of Burt's Bees.
2. Two weeks ago, I went from practicing 4-5 times a week for 30-45 minutes to practicing 5-6 times a week from 30-60 minutes, and roughly doubling my practice time overall.
3. I switched from a Yamaha Xeno to a B&S Challenger II, still using the same Stork mouthpiece.
I took a lesson today for the first time in over a month, and my teacher mentioned that I'm blowing harder than necessary for good tone.
He and I both thought I might take several days off, doing nothing more than soft long tones in the lower register.
Possibly a combination of blowing too hard and my lips maybe needing time to adjust to the increase in practice.