I wanted to let people know that I have experienced complete relief from coccyx pain since I started taking calcium supplements. I had coccyx pain for about 18 months with no real improvement. I could only sit for about an hour at a time and a total of 2 hours per day without pain, even using a coccyx cushion. Nine months ago, I started taking calcium supplements, not specifically for my coccyx pain, but because my doctor recommended it as a standard practice to prevent osteoporosis. Within a couple of months, I began to notice a gradual, but significant increase in how long I could sit without pain. Now I can sit in a chair for 8-9 hours per day with no problem, although I still use the cushion to be on the safe side.
I have never heard calcium recommended for coccyx pain, but it makes sense since calcium is known to strengthen bones. Note that taking too much calcium can be dangerous. I am consuming about 1,200 milligrams of calcium per day, which is around the common recommendation. The body can absorb at most 500 mg of calcium at once, so it is good to spread out your intake over the course of a day. I cannot be 100% sure that my improvement was due to calcium and not a coincidence, but I hope that my experience might help other people.