I agree that it is really important that you find someone at this point to help you with this. I have looked up a few places for you to get in contact with and see if they might suit. These three are all in the Eau Claire area and all offer private lessons. I do not know about their training philosophy so that is something you will have to look into. I am not trying to endorse any of these, but I am hoping to give you a place to start in your area. If you have a local kennel club in the area you can also contact them and ask for recommendations ( I think the Indianhead Kennel Club might be in your area http://www.indianheadkennelclub.org/).
http://www.abctc.com/
http://www.rudedogu.com/rdu/index.html
http://embarkdog.com/
I also agree with the poster that mentioned that it sounds like he has a problem with bit inhibition.
Has he ever broken skin? How are you currently responding when he does this? How are you correcting him?
Be very careful not to correct him in a way that might escalate or compound his problem…the suggestion of spraying him with something like mint spray is probably not the way to go.
I really do think you should get an experienced trainer/behaviorist to assist you with this. It can most likely be fixed with training...but the wrong approach could also make it much worse. Since we here have to rely only on your description of his behavior and never actually get to observe him our ability to help is limited.