I fractured my tailbone years ago and it has healed well, other than aching a bit in the winter . During my 5th pregnancy , my tailbone became agony to sit on, but this resolved itself after the baby was born. Now, I get a sharp pain if I sit slouched on something hard. Upon investigation, I have discovered a pea sized lump attached to the very base of my coccyx . It is not in the skin . I can push it under and up the inside of my coccyx, but not out towards the skin, nor can I move it to either side. I m 26, female, bmi of 19 and healthy otherwise.