I never acquired the taste for coffee, but i can drink Mt. Dew in the morning. Mt. Dew is also an acquired taste, especially in the morning. It's not as vile as beer in the morning, though pretty close. I'd get withdrawal headaches on Sunday because i don't drink soda at home, just at work. So, the obvious experiment was to switch to Sprite, which has no caffeine. After two weeks, there were two things that were obvious. First, there was a clear connection. My shoulder pain had backed off considerably. I still had restricted motion. But it wasn't getting worse.
The second observation was unexpected. It turns out that i don't really like Sprite. So, i switched to water, and i ended up consuming about a half-gallon every day. A side effect of this switch was that i lost 37 pounds (17 kg). That's because water has about 700 fewer calories than Sprite or Mt. Dew in the quantities i consume. This lost weight wasn't hard to find. I don't remember, maybe it was under the bed.
In any case, this started in February 2001. Just in case i wasn't convinced, in March 2001, i went on a job interview. They offered me a cup of coffee. Again, i don't drink coffee. But on interviews, i seem to lose about 50 IQ points. It's amazing i ever get hired. It was one of those small Styrofoam cups. I drank it. My shoulder hurt like hell for four days. I still reach for things with my left hand, even though now that's the shoulder that hurts. The pain held pretty steady until the month of October. Then the pain ramped down to zero, and my restricted motion became unrestricted. But fast forward to now. This is month nine. Every day, my left shoulder's pain noticeably decreases and the range of motion increases. I fully expect to be totally cured by month’s end. That is, if i don't fall off the wagon. It really hurts to fall off the wagon.