I think it's mostly the words and actions...
Your suggestions are what we decided to try...reinforcing his positives, uniqueness, and what makes him so special
He tends to latch on to one or two friends at a time rather than opening up to the entire class. It's happened before until he got in trouble because of what he did and that stopped it. I tend to agree that he is feeling out various things, I just want him to understand it's important to be himself
It was a bit worrying when the teacher brought it up but I feel more positive after the replies from you and Samual. Thanks for that!