I get what you're saying.
It's not right just to say "he's got a lot of change at present, he'll be okay once it's settled down" because this behaviour is ongoing, and was happeneing before the changes.
Firstly don't feel guilty in telling him off. he needs to know when things are not acceptable. If you don't tell him then he won't necessarily realise. He could shake a doll's head, or probably even yours without it being an issue. Of course he won't realise without being told that it is a complete no no. Have what he can't do very clear. So he knows if he steps over it then a consequence happens. let go things that don't matter.
I would go in and discuss with school. That way they know that you are on their side and that helps not to produce the "naughty boy label". It also helps if you know what behaviour produces what sanctions.
For my ds we found a home/school book helped. They would write down bits of his day. A day might sound like this:
"Sat on the carpet well. 
Did activity with adult. Didn't want to come at first, but did it well when he came.
Threw toy at child. Time out. 
Lunch time behaved very well. Helped put away toys at end without being asked. 
Listened to story nicely.
I could then talk it through. Saying well done, praising the good behaviour, and asking what he thought he should have done on the bad behaviour-and listening to his side. Sometimes you sympathise with his side ("X knocked down my sandcastle 3 times, and I kept asking him to do it, so I hit him and he stopped") but you don't agree with the bad behaviour ("that was naughty of X. You must have been very sad when he did that, but you still don't hit. What would have been better to do?")
It also helps you see flash points (lunch was bad for ds because he has problems hearing and he found the noise hard), and also if the general behaviour was getting better, worse, staying the same. And what worked with rewards.