Thank you for your site. It helped me in search for the right diagnosis for my coccyx-sacrum-buttock pain. I would like to share my story in hope that it may help someone.
My story (male, 33 years, living in Kiev): I had terrible pains in the coccyx-sacrum area and inside the left buttock. The pain grew more intensive while walking, standing and sometimes when sitting.
Doctors in the former Soviet Union extremely overdiagnose disc protrusions/herniations as the cause for buttock and leg pain, so I had hard time striving to find the real cause. Unfortunately, more than half of the doctors were incompetent at interpreting MRI scans.
The pain was most likely caused by effects of repetitive strain as I exercised on a stepper and swam too much to reduce weight.
The condition was quickly and successfully treated with the following steps:
a) reduction of physical activity (including walking)
b) anti-inflammatory suppositories (diclofenac)
c) post-isometric relaxation of the muscles that are attached to the coccyx and/or sacrum.
I believe this is an effective treatment for coccyx pain of muscle origin.