My best friend works at McLean's and it is the best but they are impossible to get into. And, a bit too far away for me to be present there. We have a lot of similarities in our situations. May I ask how old DD is?
His official diagnosis is a "non specific explosive mood disorder" which is sort of wishywashy terminology, if you ask me. Sort of a "name" for something they cant quite define. They are reluctant to label him as bi-polar, as that can stick with you forever and they'd like to see how he responds to the treatment plan first.
I'm wondering if you are in MA, just because if you do get the bipolar diagnosis, you are entitled to parity in medical treatment (eg., he can get unlimited therapy sessions if the doctor recommends, versus the usual 24) and he cannot be discriminated against as having a preexisting condition nor can he be charged more in future health coverage. Of course, if he moves, then he may not be protected, but it's something to keep in mind if they are considering that diagnosis.