I Think I Have A Calcium Build Up On My

i think i have a calcium build up on my tail bone extreamly painfull i have had it for a couple years but it only flames up once in a while . i think i was miss diognosed by my small town docter as a boil an they cut it open years ago witch i have been told since that they sholdnt have its flared up now and i can only just sit down also hurts when i walk