I had a very similar occurrence about 3 weeks ago.
Please read over this thread, I'm sure you'll find it useful in more ways than one.
http://www.rottweiler.net/forums/pup...blishment.html
Bottom Line: I have very quickly realized that the only time my pup aggressively bit me was during an alpha roll. They're dangerous and just don't work. 3 weeks of consistent training later, my girl offers up submission ON HER OWN, without being forced. Forcing a dog in a submission position does not make a dog submissive, just the same as forcing a dog into a sit or a down does not teach them the command.
Stick with positive reinforcement training, keeping your cool with calm deliberate control and lots of praise/treats for good behaviour. You will find a world of difference.