Referred pain

This post about referred arthritis pain takes me back: after I came down with the symptoms of AS, but before I was diagnosed with it, I complained about pain in the neck and shoulders. But the bone scan revealed severe sacroilitis -- inflammation of the sacroiliac (pelvic) joint. My doctor asked why I didn't report on that -- I was too preoccupied with the neck, shoulder and upper back pain, which was keeping me from sleeping. The sacroilitis, to be sure, was keeping me from walking properly, but it seemed a secondary thing. Also, after several months of sleep deprivation I wasn't thinking too clearly.