My daughter is on the spectrum (Aspergers) and is a very socially "weird" child.
I reached out to support groups just to get her confidence up and help her with her social interaction and met up with parents and other kids like her a few times a month. I live in a small town, it seems like very fortunately there seem to be a lot of groups out there.
Have you tried that for your son?
My son is the same way. He has speech issues so nobody wants to be friends with him. It sucks