D.C.
I was in a similar situation with my son, although he was a little older.
We decided to take the psychologists advice, that he was possibly acting out becasue he was bored in school. "If they want me to be a baby i will". The following year my son was in a different school, and the teachers immediately saw that he needed more stimulation throughout the day, and formulated a plan for him. His IQ ( I know pigeonholing...blah!) was in the well-gifted range.
Now he is old enough to speak up, and tell the teachers he's bored with this (math for example), and als to realize that sometimes he just has finish his work, and wait...
I don't know if this will help you, but I hope it gives you at least another opinion.