Suggest Treatment For Gastroparesis

My 15 yr old son has had a constant burning pain in his esphogus for over a month . With the pain he has had shortness of breathe . While admitted to the hospital they did a chest X-Ray, EKG, endoscopy, gastric emptying scan and a ph probe. They did find that he has Gastroparesis however, no medicine has worked so far to stop the burning pain. Any suggestions as to what should be our next step ?