Di, try reading the book by Steve Biddulph called "Raising Boys" it is fantastic and explains lots of things. One thing I did read was that when boys reach 14/15 their testosterone levels rise by about 800% and this is what makes them moody, sullen, angry, etc,. When their levels go back to normal so does their behaviour but that is not for ages (sorry). It talks about boys in all their stages and we got it to read about DS1 who is now 11 and omg is he starting early.

Good luck with this I know how hard it is. My DD1 is 15