as u said ir talbone or coccyx
site is hurting alot..i advise u to go to orthopaedician for further investigations like x-ray to exclude disc prolapse
..u need to immobilize ur back either by giving complete bed rest
or with a belt on ur waist ..for atleast 3 wks and then only u will b relieved of ur pain ..u also need to take some pain killers alongwith these precautions ..
so relax and take complete rest with an x-ray done ..
al the best ..