I have post inguinal hernia pain that is caused by the mesh encasing nerves causing all kinds of pain on one side, but to have true abdominal wall pain is usually an indicator or some systemic problem yet to be found. I can't imagine that with ultrasound and x-ray that anything serious would be missed in the abdomen by the doctors. There are books on chronic pain in the abdomen that you can get, so it is definitely a topic that has been studied. However, it is not a common practice for doctors to treat abdominal wall pain as much as say a chronic joint pain or back pain so you probably really need to push doctors to investigate as much as possible with imaging and definitely try physical therapy to strengthen core if you can. Many chronic pain problems involve small peripheral nerves that are rarely studied as pain generators yet they are exactly that. With experts like Dellon Institute trained physicians, you have better shot at a definitive diagnosis.