I hear you having 2 questions: what is the source of your son's pain and what can be done? For the first question, I would say that you have described a reasonably extensive workup. The source seems not to be structural because it is on both sides and crosses multiple dermatomes. You didn't describe any trauma that preceeded the onset nor that your son has any identified chronic diseases or unusual birth conditions.


You have not described weight loss or loss of appetite, night sweats, fever, or other systemic symptoms sometimes associated with cancer or immune system disorders. I might re-scan the area in the clavicle after a month or so to see if it changed (osteosarcoma with a paraneoplastic pain syndrome). Get a vitamin D level. Your second question, of how to treat the pain now, is easier. Your son is taking a reasonable dose of gabapentin, a medicine that is pretty good for pain felt to be neuropathic in nature (no tissue damage but the nerves are sending false pain signals). The next 2 medications I would consider are dexamethasone and methadone, effective for tissue damage, organ distension, inflammatory, and neuropathic pain types. A doctor who works with these medicines frequently should prescribe them to stay safe and also be effective.


Keep pressing for a diagnosis but treat your son's pain aggressively in the meantime.