My mouth hurts like a mother! Help?

Every month I get around 2-3 canker sores from accidentally biting myself while eating, talking, or chewing gum. Each time, it gets infected and stings and burns. Is there any way to stop myself fom biting my cheeks? I currently have one and it's huge. I'm thinking of using baking soda and water to stop it, but win I started using that to brighten my teeth and had a small sore that hadn't been infected, it got in my canker sore, which was tiny, and It hurt really bad but stopped the sore. If I put it in my big sore, I might die. Help?