My thought are with you. I too, lost a son when he was 17 years old. His cause of death was unknown and that was the hardest part. He hadn't been well for 2 years prior to his death and I kept taking him to the doctor and she kept telling me he was doing it for attention and I knew he wasn't. Test after test came up with nothing... Then he died.... still don't know why. So, I know your pain. He would have been 40 last December 22.