To me it seems that this could be either two things. Either he isn't getting anywhere near enough exercise or he has a small case of separation anxiety. Are you crate training him? I'd do that. Once he's crate trained you can work on fixing separation anxiety. You put him in, leave for 5-10 min and then come back, you do this a few times and then start to increase the length of time that you're away. If is a lack of exercise you need to play with him a ton more. That being said following you everywhere is normal for a doberman, puppy or adult. They are very "velcro" dogs, they will stick to you like glue. Most doberman owners cannot go to the bathroom alone.
Edit: I guess giving him his own room is pretty much similar to crate training so my advice on that can remain the same.
Edit: I guess giving him his own room is pretty much similar to crate training so my advice on that can remain the same.