My son has benefitted from being a part of a social skills group. He's been in weekly sessions at school and at a psychologists' office (they specialize in autism spectrum and SPD). He can also miss social cues of someone trying to be nice and wanting to become friends with him, so they practice real life situations, learn appropriate behaviors. He seems to do better when a situation has been scripted for him. We had his PPT/IEP meeting at school last week and his teacher gave this example of his progress: he had to go to the office to make a photocopy of something, he got halfway there, then turned around and went back to the teacher. He told her he didn't know what to do or say. She told him to ask Mrs Allen at the front desk to help him make the copy. And he did. A year ago, 2 years ago, he would've gotten halfway to the office and stopped dead in his tracks. He would've been frozen there not knowing what to do until an adult found him to help. When he doesn't know what he's supposed to do, he freezes up, shuts down--or at least he did. He still has a journey ahead of him, but he's come so far.

Talk to your son's doctor about the next steps. Find an OT. Find a psychologist who treats SPD (or at least treats autism spectrum). Hugs to you and your son!