I am now serious and not kidding, have you been to see a doctor, because I tell you for why, when I was a young lad, I was doing regional motocross racing and winning every race until jumping and landing became a pain in the Coccyx and I went to my doctor who found I had an advanced state of cystitis in that bone and he had me operated within the week and I was ok ever after. The doc removed a whole section of the last bone which had about 8 cysts.