FrNJMom - yes, I thought so too...total non-expert however.
Throwing in my two cents, yes the change sounds very abrupt! You should look for a particular event that might have triggered the sudden change in outlook for your ds. Might be something a counselor could work on with him. I was told by a dev. pediatrician that some kids just need a neutral party to talk to sometimes to work out issues they have a hard time either telling more familiar people about, or even realizing themselves that they are occuring. This makes sense to me. Good luck to you and ds, Elh!