How Can Coccyx Injury With Pain Be Treated?

My wife had a road accident 3 years back and she got her tail bone badly injured. We consulted many doctors and were told by few that it would go away by time, few said that it can never be cured. though the pain has reduced to some extend, but still she finds very painful sitting on hard surfaces. This could be even more painful during pregnancy. Can you please suggest a good treatment for this?