It's coccydynia, pain in the tailbone. The pain is triggered by sitting and often results from trauma, such as falling on the buttocks, or prolonged sitting.

Treatment becomes more challenging for persistent pain. While the approach varies based on individual factors, methods may include manually adjusting the misshapen coccyx, corticosteroid injections, trigger point injections around the area, using nonsteroidal anti-inflammatory pain relievers, and sitting on a doughnut-shaped cushion until the painful condition improves.