5 year old with low confidence

Hello
I have 5 year son who has low self esteem and confidence. He crus really bad with anger when he's told no you can't do it . He cries when he knows he did something bad. He cries when u tell him he didn't do something right. He cries over small things and stomps his feet with anger. I tell him he doesn't have to cry just say sorry and that he won't do it again. But I feel like it's because he doesn't have confidence in how he is and who he is. He gets social anxiety he doesn't like crowded places he always clings to me in a gathering. On a Normal day he will stay close to me won't go in another room to play even with his baby brother or cousin. I need him to be confident in what he does and not be so sad when he does something wrong. He doesn't like to try anything new in fear of he can't do it.
He's average height and weight. He eats carbs but not fruit. Please help