Which treatment/procedure is best after 3 back surgeries-including fusion to relieve pain?

Options. There are options to treat your pain, including medication, interventional pain procedures, and spinal cord stimulation.
Depends. The hope would be that if you had surgery or surgeries done, that you would be doing so well that nothing else would have to be done. If you are still having symptoms, then the bigger question is what is the cause of those symptoms and what are the options to treat them. Don't hesitate to discuss directly with a specialist.