Child's behaviour at school devolving HELP!

Hi

My 7YO son has had his autism and ADHD diagnosis since August last year and had an EHCP in place at school since November.

He is generally a very happy little dude and at home and at his wrap round (before and after school) care his autism/ADHD does not cause any major issues, but, since he went back to school from the the Easter holidays though his behaviour has devolved, daily issues with running away, hiding and climbing book cases and yesterday he was so dysregulated that he slapped his teacher and got an internal exclusion! We are in regular meetings with the school, talking to them pretty much daily trying to find ways to make things less overwhelming for my little boy to improve his coping skills but I am at a loss as to what else to suggest to them as there is already so much in place. 

Has anyone been in a similar situation or does anyone have any advice that could help?

Thanks for reading

Li