So, your family fell into the huge crack in services... as soon as he got labeled "ED", he got NOTHING of value. In reality, he wasn't ED. He was/is dealing with pervasive developmental issues, which should have had intensive interventions very early. In addition, at some point, these "mood swings" have shown up.
He is "hanging with a very unsavory crew". What else do you expect. He has major social skills problems, and neurotypical kids are about the most cruel beings on the planet. Outcasts are welcome by the druggies, because the only rule is that you have to use drugs.
It's such a challenge to get resources for a supported move-out. Which is probably what he needs, but not what he wants. I'm guessing that he finds change difficult to manage?
