would look at his diet. Low sugar and cut out as many preservatives as possible. A poor diet can send some kids feral. A great Australian site is www.fedupwithfoodadditives.info In Australia there is particularly bad preservative called 282 here which is an anti mould preservative found in breads, refridgerated pasta, cakes etc. I cut this out of my daughter's diet and after a week the improvement in her behaviour was amazing. It doesn't work for every child but certainly worth a try.
I got called in to see his teacher this morning and she thinks there might be something serious wrong - I'm guessing at a form of ADHD or Autisum as she has requested that he be sent for a referal through the school.
I'm a little shocked, but I'm glad that something is being done, and if he does have a problem then hopefully we will be able to tackle it once we know what 'it' is.