Probably you were advised a cap on the root canal treated teeth which for some reason you didn't get it done. As the tooth crown part has broken off it's very difficult to restore it,its a better idea to get it removed.
The removal of a root canal treated teeth might take a little more time but as such not a very painful experience.
For now before you get it removed you can take tab ultracet once or twice daily.
Next Steps
Get the teeth removed at earliest.
Health Tips
Also go for crown/cap after root canal treatment.