Following the very difficult birth of our last child sixteen years ago, I noticed I had excruciating pain in my coccyx. When I asked my O.B. about this a few days after delivery, he informed me that my coccyx had been broken during the delivery and that there was nothing that could be done - that it would heal on its own.
Over the years it has improved, but I still find it difficult to sit cross-legged on the floor and a few other positions cause discomfort. My biggest complaint is that about six or seven times a year, I get a severe unrelenting pain in the coccyx.
By trial and error, I have found that if I lean backwards over the arm of the sofa with my legs resting on the floor or dangling, I can "reposition" the coccyx and get immediate pain relief. In an emergency, I have done this in my car also, with a little more difficulty. Be sure that the coccyx is on the arm or on the curve of whatever you are using to get the maximum pressure.