have you talked to the school? of course i am sure you have

but there might be something going on in the class that has him upset or sometimes you can get staff that think they dont have to follow the way a program is written in order to make short cuts never mind that our kids need consistancy most and that those programs are written the way they are written for a reason. maybe a second opinion might help as far as the psychiatrist goes. as far as my son goes though and this is not the case every time... he goes through a defiant stage and has a small regressive time then starts to trudge on a head... the only time he seems to make any significant gains is after he has tried his hardest to not do something... and he tries really hard not to do things

and has his time to let us know that he objects to life in general because we are asking him to do things and after he finally figures out we are not backing down then he moves on and does what he is suppose to do.
we had trouble with one ABA instructor (dont know if you have ABA there but generally here they are people who work in the home with your children one on one. they work on specific goals and do the same thing over and over ever day until the kids get it.) anyhow, she kept giving in to isaac's tantrums and at the end of her short time with us she was having to leave early several times a week because isaac refused to work with her. he only got worse about that until we got a new instructor who knew what he was up to
perhaps at the new school someone is acting like that... maybe they think that your son needs a little slack and he has learned that he can get away with anything if he acts up enough... just an idea...

my son might not be so hot socially but he is the KING of manipulation

a direction to look for the moment anyhow. you might need to meet with the school and make a plan of how to treat some of his behaviors so that everyone is acting the same towards any unwanted behaviors. this might help... might not if its medical though. wish i could be more help

G-Luck, though!