My son has suddenly started to get incredibly angry about things. If he gets frustrated he works himself up into a frenzy & will throw it around & generally try to break everything he can reach. He frequently hits & pinches me. He has always been prone to frustration and we're teaching him to pause, take a deep breath etc. This current behaviour is well past that & has come on pretty suddenly. Does anyone have any ideas? I can calm him down from these rages, but I'm just concerned about why he gets them in the first place, and why his behaviour has changed so suddenly.