Rough Housing, Bullying and Just Being Boys ... in the Eyes of a 4 Year Old

Hi there

I have a 4 1/2 boy who has been recently diagnosed as Highly Functioning ASD and Sensory Seeking.  He is a lovely boy and very extravert.  However we have had to move 3 schools in less than a year because they belived he was just misbehaving vs. something was profoundly wrong.  We are finally finding our feet post-diagnosis.  

That said, my son has had lots of friends and done relatively well socially.  Howeve, he lacks empathy and social awareness.  He often comes home often saying other boys are beating him up.  Even his friends are horrible to him ... as they run after him and rough house.

To some extent I know a few of the boys are truly bullies. Some though I think are just playing. My son can't differientate and we have seen at parties how he gets beaten up and just lies there ... unsure of how to cope.

Initally we told him to tell the other boys (whether playing or not) to stop and then get an adult to help if they wouldn't.  That hasn't really worked.  

Personally i don't know what to do and advise him in a way he understands.  He needs to learn to stand up for himself but he also has to learn when children are truly being mean vs. playing.  I could really use some advice or resouces.

Would anyone have any ideas?