I have a 5 year old son that has a chewing obsession. He always seems to have his mouth on something. When he gives you a hug, he's really going in to chew on your hair. He chews on his stuffed animals' arms, or is always biting their fur off. He chews the clothes he is wearing, corners of blankets he is under, books he is holding, ties off the bathrobes, you name it. How can I get him to stop this behavior?