Along the lines of what Maryann said: are you able to get a hard copy of the initial diagnosis, as well as all of the test results to date (at least, if there was a different diagnosis)? It would just help to understand disease progression, and for you to create a timeline of diagnosis, tests, treatments, radiation and symptoms. A woman posted recently about creating a medical/symptom timeline, and I can locate this for you if it would help.
We can help you conduct research, based on specific questions from lab results, while we wait for an expert who may be able to fill in the (information) gaps.
We're here to help you talk with your doctors, and figure this out. You sound very empowered and a great advocate for your son.