I am linking a thread for you, that has a whole lot of good advice, very similar situation to yours:
http://www.yorkietalk.com/forums/gen...sparate-2.html
Also there is an article in the library, How to Rehab a Puppy Mill dog. While your dog is probably not from a mill, some of the behaviours are similar.
If you follow the advice share on either the thread or the article, do it consistently and daily. Try 100% for two weeks, then if you are not successful, ask your vet for a recommendation to a good behaviourist trainer.
And Lastly Welcome to YT!