Crystal balls welcome.
Mostly he's happy enough..then Bam! He gets up set and destroys, I mean destroys things. A week ago he totally destroyed his bedroom (desk, chair, bed, phone, glasses, cupboard all wrecked) because his blackberry pie wasn't working. This week it was because he couldn't mend his bike as he didn't have the necessary bolt (DH had taken him to the shop to buy the right bolt, but somehow it wasn't going right) - Cue pictures being thrown at DH, hoover thrown downstairs, his homework set alight.
This morning he didn't have a lunchbox (because he had smashed it in a rage) so was distressed his lunch would get squashed in his bag, and stormed out of the house with no glasses (he really needs his glasses as he's a +6).
His anger seems mostly directed at DH and I. I'm making very sure he's getting enough food (he can really pile it away atm, lol!) and exercise (he will happily go for an early morning bike ride of 10 mile+ on weekend mornings)
Last week we had parents evening, and I was told over and over by each subject teacher his behaviour is perfect in school, and he is working at A/B, which no effort...and if he chose to put in some effort he could easily get A* in most of his GCSE's. (He couldn't be bored, could he? 
)- Don't flame me - I know how that sounds! But DS had his primary school teachers "on their knees" by the end of the week, as he was so challenging/off/task/willful, if he wasn't appropriately challenged.
Before speaking to the teachers, I had suggested to the head of year DS needs all pressure removing, as he seems very stressed.
We've had no major changes in our life recently, but DS is behaving just as he did when he was 4.5yo, we moved house, soon after DS2 was born....DH and I were feeling smug we were providing DS with a lovely in a desirable area, and a sibling. With hindsight, DS1 didn't share our sentiments.
He does suffer from anxiety and is diagnosed with Aspergers. He was a bit worried about a trip he was going on this week with school (it's a really fun trip, and he doesn't do fun) but he seems to have relaxed about that.
As I said, Crystal balls welcome.