Where are you located? I suggest that you visit the closest major medical center associated with a medical school such as UCSF, Stanford, or the Cleveland Clinic, Johns Hopkins, etc. This will give you access to a team of specialists who will work together to address the different areas - orthopedics, neurology, pain management, rehabilitation and psychological support as well. You'll also have access to the latest technology and treatment by experienced surgeons.
While many of the posters offered helpful information, each situation is so unique that it's best to find a specialist that you feel comfortable with and is willing to work with you to help you understand what your current problems are and what the current treatment options are. Your current pain may be unrelated to the original problems that required surgery.
I had a problem with painful hardware following a successful fusion. The pain was intolerable and stopped after the hardware was removed but before operating, several diagnostic tests and injections were done to see if the hardware was the issue.
Good luck.