I know this will sound wrong, but hear me out. Chronic pain can be caused by the brain. This is especially true when there are no physical explanation the cause of the pain. It happens because the brain was trained to react when the body experienced the acute injury. The body heals but the pain doesn't go away and may even worsen. Its not the person fault. Its how our minds work. There is a good book on the subject Chronic Pain Rehabilitation: Active pain management that helps you get back to the life you love by Even Parks.
After my a long term bought with a bowl obstruction my insurance company (United Healthcare) referred me to intensive cognitive behavioral therapy. I worked with a therapist and a para professional for 8 weeks to reprogram my behavior and thinking to reduce and eventually eliminate the pain. Some people resist this because they think that it indicates that pain is imaginary, but it isn't/ Its real pain that doesn't have a physical solution. Our bodies are amazing things. Our brain will do so much in an effort to protect us and sometimes it over does it and gets caught in a loop.

Denise