Whoa..there is definitely something wrong with your vet's advice
. Crate him all day until he knows your the alpha
? Pretty shocking that she thinks this is one of the solution. A relationship with a dog has to be built based on trust, respect and kindness. I agree with other posters that little things like you go out of the door first, walk in front of your dog and only let them jump on the furniture when invited works and should be practiced; not crated all day.
Also, I think you have been doing a good job in socializing Einstein at the dog parks and going out for walks. Definitely when he runs back to you and you see other dog/dogs following him and he feels uncomfortable, you need to protect him by directing the other dogs off of his back. I think you are doing the correct thing. Do not follow what your vet say or else your dog might revert back to square one! I say look for a good dog behaviouralist. Some dog trainers could be weird too so be sure to find one that uses methods that are kind and build trust and respect. I have to add there are some dogs that are shy and might not like a dog park setting when there are too many dogs to handle but if you can set up a playdate with dogs that you know and just a few of them at once, it will be better.
He is really cute and he is definitely a Yorkie no matter what other tries to tell you. I really don't see any Silky in him
.