I have a son who is like this. At home he is great but put him in public and he can freeze. They had a magician at school he said it was scary, I asked him why he was scared and his reply was because he was scared he was going to make him get up on the stage.

I haven't read this book but have meant to buy it, I'm pretty sure it was called The Highly Sensitive Child, I think someone on BB recommended it a year or so ago.