Your child has started looking at himself as an independent entity with a lot of capabilities. He is basking in self-worth due to all the praises and appreciations that he has been getting. Any kind of criticism, even the slightest, whether it is from a friend, a parent or a teacher will be enough to bring a flood of tears and sulking. He is still not emotionally strong enough to handle criticism and will feel hurt to know that other people think of him any less than what he thinks of himself.
What you need to know
It is important for us as parents to make our children understand that criticism is a part of life and will come their way always. It is important for them to learn how to handle criticism positively. This we can do by setting an example for our children. When children see their parents handling criticism constructively, they will learn to do the same.