been there! try not putting him in his crate when he does this. his crate should be a place he wants to go, not one that he goes in because he is being punished. Can you try spraying him with a water bottle when he does this?? we did that with Layla and she hated it... stopped that fast! or a can with pennies?? many use this for barking but i'm sure it woudl work for biting.. if you have a sensitive guy like Layla you might not want to try this.. Layla would hide all night if she heard that noise. LAST resort you can spray your hands and feet with bitter apple
this stops dogs from chewing (usually on furniature or cords) but it will make him hate chewing on you pretty fast!