Welcome, Lala. I'm so very sorry about the MST. Thank you for serving for your country; I'm sorry that you had a horrible experience.
My son began his angry outbursts at age 3 as well. Like you, I am reasonably certain that no one physically abused my child. I think sometimes, with boys especially, that anger is an "easier" emotion for them to display than other "softer" emotions like fear or sadness. When a child is young, I think it is very difficult for them to articulate what they are actually feeling. Instead, we get horrific tantrums and aggression.
I am appalled that the psychiatrist is not helping your child. When my son reached his worst stage, I wrote a letter to the most respected child psychiatrist in my area begging for help with him. I had heard that she would not accept new patients, but something in my letter must have sparked her interest. She agreed to see us. It does not sound like you have found the right psychiatrist or therapist for your son yet.
We lovingly refer to him as the Hulk when describing these behaviors. He can be the best kid and then it's like a switch has went off and he is no longer there.
I think I have actually seen a child like this once. I taught preschool for 9 years and I had one small child totally wig out one day. His eyes went blank as he raged through the classroom knocking over everything in sight. The other children were terrified, and my director scooted all of them out of the room. I stayed with the angry boy. After a few minutes of destruction, he seemed to wake up and come back to consciousness. He looked around at the destruction in the room and seemed to recognize that he had caused it. I don't think he remembered actually doing it, though. We had to expel him from the school. His mother was distraught, and I advised her to seek a neurological evaluation for her son.
I am also including a link to the parent report. You may find it useful to gather all of the information together to give any new doctors you may see a concise story of your child.
http://www.conductdisorders.com/community/threads/parent-report-updated.225/#axzz47RXUUavX
Stay strong. One day you will find a way to help your son.