This character's family is walking on eggshells to keep from setting him off, when he does get "set off" by trivial things he refuses to speak and shuts down into a catatonic state. He explodes with rage on himself and other people if his buttons get pushed. He is able to self-care and he's otherwise intellectually appropriate for his age. The problem has been there since childhood, but it's getting worse and he's no longer able to be in school.
Where would a doctor's instinct lead? I don't really need the name of a specific disorder, just a direction the doctor would start looking in first? Spectrum disorders? What avenues would a psychiatrist explore to try and find out the problem, especially if the teen was unwilling to speak or ignored her completely?
I've googled and wikied "pervasive developmental disorders" "mutism in teens" "selective mutism" "teen refusing to speak" "autism spectrum disorders" "horses not zebras, psychiatry" "PDD-NOS" "intermittent explosive disorder" "How do psychiatrists diagnose" "psychiatric method" and about five thousand variations on "DSM IV free online"