Poor itty bitty thing. I won't ask why the breeder couldn't let him stay with the mommie as I probably know so I'm so sorry that this happened to you. We have a few of these type breeders on our side of the globe, too, so they are all over. I don't remember a lot about puppy-raising specifically as to food, etc., but our puppy guides here in the YorkieTalk Library are so helpful. Here is a link so you can read up on just about every subject. I particularly like the Puppy Care Guide for the basics. It is the 5th thread from the top. In addition to the current advice you'll get, there's all of the information to fall back on or use in the middle of the night when you need an answer to some basic question and no one is on YT right then.
Puppy Care and Puppy Info Library - YorkieTalk.com Forums - Yorkshire Terrier Community