Canis-Lupess! Wonderful post.

The last thing you want to do is make your son more of a threat to your Bulldog. First and foremost, you must manage the situation. She can never be unsupervised around him and vice versa, in case he's doing something to upset her without you knowing. Babygates would be a very good idea!!! As would containing her in her crate when you aren't right there. Check out http://www.iaabc.org/ for a behaviorist near you. A consultation with a trained, knowledgable professional who can see what's going on first hand is essential in situations this serious.

In the meantime, make your son's presence the MOST positive thing in your dog's life. Every time he walks into the room, click and treat her repeatedly. Every time she glances at him (in a non-threatening manner, of course) click and treat Every time he is nearby, click and treat. Use the highest value treats possible, and keep their interactions very calm, brief and positive. Don't allow your son to approach her at this time.