6 year old has sudden outbursts. Please help

[Dibell]

Our 6 year old has always been bit naughty like kids can be but at school he has always been extremely good. The strange thing since a few weeks ago he has been misbehaving in class chatting, and as teacher says all if a sudden as if something takes over him he becomes naughty and doesn't listen to his teacher. He's not aggressive or verbal just misbehaves. Then after short while back to normal.
We have been doing all we can to see if we can get to the bottom of it. Even been watching his diet and have cut out his milk for past few weeks and have seen a big difference in him but something is still there.
It's causing problems at home with the constant having to tell him off and putting a strain on our family. We are really worried about him. One minute he loving little boy then all of sudden it's like monster comes out in him.
We have read about Dairy problems causing behaviour problems ! Has anyone else had this problem?
We have Been to drs 3 times to seek advise and to be honest it was a waste of time they were no help at all.
Anyone been through anything like this or going through this.
All advice be welcome.

Usually there is some kind of outside trigger for an outburst and if you can avoid the trigger (and later on teach him to avoid the trigger himself) then you can avoid the outbursts too. Or it could be that you are just a bit too quick to respond to the naughtiness with a telling-off and you might be better off saying nothing and leaving him to get on with it and get over it by himself. Depending on what he is doing and how long the naughtiness or outburst lasts.

But it's hard to say. Especially I'm not clear about what you mean by "misbehaves" and "naughty" so can you give a couple of examples of what happens - what you were all doing, what he said/did, how you responded, how it ended?