I would do like Guille said and have him tested. He's probably got an issue that's never been identified and he needs to deal with it if he's ever going to get a job and be independent.
We're seeing a CBT (Cognitive Behavior Therapist) at $100/session. It's more action oriented than "how do you feel?" therapy. It is more goal oriented and I think that would be good for him. He might find his goals and then be motivated.
We're seeing Lisa Lang CBT in Flower Mound.
Make the school do the testing for a learning disability... I can't believe they haven't before... it's his right... and paid for by the State.