Dr. Drake did discover with x-raysthat he had a large mass in his chest in front of his heart. This was compressing his lungs quite severly, causing the fast and difficult breathing. He was going to try and draw some fluid out of it to give him more room to breathe, but was unable to get it done before it killed him.
Dr. Drake believes it may have been an abscess, as his airways were also quite inflamed. The subject of necropsy was brought up, but I turned it down. Couldn't stand the thought of it. Thanks everyone for the sympathy.