An hour or so after coming back from tennis at the park I felt some discomfort when sitting down. The discomfort wasn't too bad, but it felt like I was sitting on something. I woke up this morning to find a golf ball sized bump at the bottom of my tailbone and some pretty bad pain. Where the hell did this thing come from? I may have slipped and fell on my ass while playing tennis, but i don't remember any significant pain. Has anyone experienced anything similar in the past and how long did the pain last?