Hi! I have a 2 year old male shih tzu and ever since he was a puppy he would always nip me and my family. Whenever we would touch his head or try to carry him, he would always nip us which has caused us to have wounds. And he would always be possessive and would try to bite us whenever he gets our things and we would try to get it back from him. What advise can you give me to stop him from nipping us? Thank you.