POST OPERATIVE PAIN

To whoever may help;
My problem is ostensibly a nerve problem. In 2001 I had a Radical Nephrectomy. Since then I have suffered with ongoing pain, which gets quite bad especially if I become stressed or have any illness. The pain starts as a pressure pain which radiates and aches then develops into sharp pain. During the operation a section of the 11th rib was removed and as I understand, the intercostal nerve that is associated with this was severed. The area where this rib is located is where I get the most pain. I spent 4 years at a Pain Clinic, where I was given a list of various medications including Axsain cream, Amytriptyline and Gabapentin. None of thes had any effect.  Gabapentin made me quite ill. Finally I had Intercostal nerve block injections that also had no effect. I was discharged from the Clinic as they had no other triatments available. As a parting shot I inquired about using a TENS machine, which which was thought would be unlikely to work. It was the only thing that did have some effect and has since been of marginal help. It is useful for discomfort but is not much help with severe pain. It is also impractical in hot weather or if you are physically active as the electrodes dislodge and give you a hefty electric shock.
I suffer from anxiety and depression, which also has a detrimental effect on my pain. I am desperate to discover what is the actual source of my pain as I have doubts that it is the severed intercostal nerve. Until I can determine the actual source of the pain I am unlikely to get the treatment I need.
I would be most grateful for any opinion or information that may shed some light on my situation, Thanks.