One thing to know about the breed is that they are pretty fragile (both physically and emotionally) as puppies. Dobies really get attached to their people and aren't happy until they are right with them (in contact with them). If you yell at him or hit him, it can make him skittish or anxious for life. This isn't some pop-psychology BS. Read up on the breed and dobes as puppies.
These little guys can be difficult as pups, but they grow into one of the smartest and most loyal dogs you will ever have.
Good luck. They're only puppies once, and then you'll just remember how cute they were.
My dobies.