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I am sorry I dont really have an answer for you but it sure sounds like you need some good advice and quickly.It might be a dominance issue but I am no expert so dont quote me on this
IMO this is a problem that needs to be addressed right away or you might be in for some real problems in the near future.
You will get good advice on here for sure from people who have had a lot of experience with yorkies.
Good luck with him anyway.