Lost, The person in crisis does suffer from quite a few ailments. Some of it is the depression talking and others are age, stress related and others comes from trying to burn the candle at both ends being a kid and in an adult body. BTW, if you read up on depression, you will find that many of them suffer from pain, both real and imaginery. There is a ton of information on what they experience in the way of pain, etc.
The sleep issue could very well be because his mind is going 90 miles an hour. I know that a few have said that they are afraid to go to sleep because they may die or their guilt takes over and they remember what they've left behind. Guilt does tend to come out at night when everything is quiet and they have nothing else to focus on.
I know that you are worried about him, but he's been to see the doctor and hopefully the doctor will work with him and get in on the right track. If he wants to talk, listen to what he has to say. He most likely doesn't want you to tell him what to do right now.
How are you doing?
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.