Thankfully, I am back to practicing and feeling good.
Lesson learned: Do NOT overwork one’s aperture corners. I did the first 3 range-development exercises. I spent a lot of energy gripping my little finger. Then, I decided to fill out an entire practice progress chart starting with 60 bpm up as fast as I could, and as long as I could.
Today, I did a check-up on my lip slurs progress. 60 BMP softly for a minute, loudly for 20 seconds. Then, I about 160 BMP soft and long, and loud and long. Finally, I slurred at 216 BMP. I rested a minute between each.
Rest as much as you play will be adhered to while practicing.