M.,
My sister, was pretty much born with depression. Well, probably not...but she was depressed from a very, very young age. Much younger then your son. Family counseling helps, because it really is something the entire family needs to learn how to cope with. Play therapy is really helpful. Like others, I recommend finding a support group. For your son, one on one time might help. My sister really lacked intimate attention. Meaning, attention given just to her and undivided. Going out to eat, doing a puzzle with no distractions, etc. The few times my parents did this, it helped. Incidentally, it helped THEM too. Sorry you're going through this. Definitely reach out into your community and find other folks in your boat. There is nothing like other parent's personal experiences to help yours.