Suggest Treatment For Having Mass At The Right Base Of Skull

My 14 year old son has been suffering from severe headaches since Sept 27th (2-1/2 months). He has had a Cat Scan (which showed sweeling of the 4th ventricle), which led to an MRI. The neuro surgeon who read the MRI said it was of no concern and not related to the headaches. (Said it was just a mega cistern magma.) He was prescribed Endomethicin (which did nothing) and was then switched to a once daily antihistamine, diet restrictions, and physical therapy for range of motion issues with his neck. At several appointments he and I have pointed out that there is a fatty area at the base of his right rib cage (he is very thin) that causes pain when he runs. We were told it was nothing . His PT has indicated that there is a mass of (hopefully muscle) at the right base of his scull that does not respond to manipulation and therapy. He now has extreme pain both in his head and in his chest. Everything I find on line points to firbous tumors. What advice would you have for pinting his physicians in a new direction?