I went to pick DS (4) up from reception class today and was called to one side by the teacher. He's not had a good day - has spent the day hitting other children and throwing things at them. How do I handle this? They asked him what was going on and he couldn't say (although they did say they he always admitted it was him doing it but couldn't explain why he was doing it). He just said to me that he was feeling cross with himself. Poor teachers were clearly at their wits end with him. He's usually easy going and eager to please but not today 
When I questioned if he was usually like this at school they said not really, although he has gone down hill over the last few weeks. At home, he's absolutely fine, no problem at all, easy going and very sweet.
As I said, I've tried to talk to him about it, but he can't articulate why. There is nothing worrying him as far as I can tell, he was just lashing out at anyone who came anywhere near him. Should I discipline him at home for bad behaviour at school? Seems sad if he's had a bad day at school to keep it going at home, but I want him to understand that I don't think its acceptable behaviour.
I'm probably paranoid now but I'm wondering what on earth is wrong with him - does he have some problem that is just making him anti-social? He is struggling with his hearing and perhaps this is making him frustrated? I didn't think his hearing was that bad though (he has a follow up appointment in Jan).
Or should I just put it down to a bad patch and hope it gets better?