Webstermum,
"Tried to give him a hug just now and he flinched away like I was about to hit him"
I guess that's one of the hardest things about having one of us around. We don't 'do' the signs of love that people need from us when we need to. And hugs actually can hurt as much as being hit, which is why we flinch away . This is SO difficult to understand sometimes, because if we prepare ourselves and balance our lives moment by moment, we can build up enough 'safe space' to volunteer a hug, a kiss. But if someone does it to us when we're already at maximum overload, it's really scary and it hurts.
And of course people don't want to hurt us or scare us. I get people putting an arm round me, or a hand on my arm, or elbowing me to make a friendly point, or shaking my hand, and it all hurts, but I know that they mean well. If hubby goes to hug me unexpectedly, I know that I pull away, but at least at my age I can explain.
Hugs: sorry if you've tried all this already....Try giving him some safe space after school, a quiet zone where he can chill out and pull something round him like a duvet. And when he's had the time to just switch off, try asking for a hug, but hug him through the duvet. It levels out the sensation of pressure for some of us, and is easier to cope with. Might not work, but it's worth a go.
With all three of us with disabilities and someone always needing something doing, (and me growing up as a young carer to a very ill mum as well as having an ASD myself) I really do appreciate how hard it is.