I had absolutely debilitating pain in a hip joint as if I had a handful of needles loose in there. I had it for several months, I had an MRI, a bone scan, tried physio, acupuncture and what have you with zero effect. At some point got a "procedure" scheduled for some sort of steroid injection directly into the spine column and was prescribed some nasty anti-inflammatory pills to "prep" for the thing (but in the end decided against the whole thing). The only thing that helped _a bit_ were the 600 mg Ibuprofen pills.
In any case, saw this book recommended here on HN, picked it up, read a quarter and realized that it applied. I was under an enormous stress at the time, both on work and personal fronts. On the work side I was running a one-man project with several thousand active daily users. On the personal end we just had a kid and the massive lifestyle change that came with it. A couple of days after realizing that the stress might've been the cause of the pain, the pain disappeared. Just - poof, gone. This was over 10 years ago and it never came back. The end.