Second follow up RUQ and back pain

This is another follow up to my RUQ question that has now also developed into a a right mid/upper dull back ache since November 08. I provided details of my symptoms and medical tests in my last post in January. Since then, I have been back to the GI doctor who has ruled out 99% that my condition is related to a liver or GI issue including the hemangioma. The pain levels have been relatively constant (3-6 level) and have not subsided for 7 months now. I went back to my primary care doctor last month after some physical therapy which was not effective. He did not want to order another x-ray since I have had so many tests that have been negative and it would have shown up. His final diagnosis is a chronic pain syndrome possibly brought on by the loss of my wife in 2006. His recommendation is deal with it or try a pain management specialist. My question is should I pursue this any further with more tests or should I accept the diagnosis? I just read about a case of a guy with upper back pain that turned out to be lung cancer that made me a bit nervous. My doctor has ruled that out, but I am still skeptical. I believe I asked you last time if the thoracic and cervical spine MRI would have identified a lung tumor causing pain on a nerve since both came back with no mention of the lungs but I'm not sure you directly addressed it. Would it? Wouldn't the pain have progressed after 7 months or other symptoms show? (My Dr. believes the longer I have this, the less likely it is a serious condition). Should I just go to the ER and get an x-ray? I would like your opinion on the likelihood that this is a cancer since there had been no noticeable progression or respiratory symptoms? What would you recommend as my next step? Thank You.