I happen to have this same problem. Some people are just more predisposed to canker sores. Some theories suggest a zinc deficiancy. Consider supplementing this.
Since you're one of us lucky people who get these suckers often. Let's educate ourselves:
http://en.wikipedia.org/wiki/Aphthous_ulcer
A canker sore is an ulcer. Wonderfully, we know about as much about mouth ulcers as we used to know about stomach ulcers. Because of this, we give mostly the same diagnosis. Which is that it's cause is unknown, but perhaps stress aggravates it. (What doesn't stress aggravate?). Now, I don't know about everyone. But in my experience, this is what's up:
What's certain is that small cuts and damage on the mucous membrane of the mouth is what triggers it. Other causes are incredibly numerous. Infections of many kinds. Typically herpes or other virus, but also bacterial or fungal infections of many types.
In most cases, stopping the initial outbreak, especially after damage has occurred is pretty much impossible if you are the kind of guy who gets them a lot. However stopping the worsening and speeding up the healing process is possible depending on what causes the secondary infection (What makes it grow). My preferred method is that if I start to feel the onset of a canker sore. I rinse my mouth very often with a strong mouthwash. I try to do this at least 2-3 times a day, if not more. A proper mouthwash mind you. Corsodyl is a brand that has chlorhexidine digluconate in it while Listerine does not!!. Chlorhexidine has strong antibacterial properties (It kills and prevents new growth). It also to a degree counteracts fungus. That's a pretty good match for our common reasons for canker sores.
Note that chlorhexidine will screw with your tastebuds and is not recommended for prolonged use.. For more reasons than the fact that it takes away your tongues ability to make sense of things. It can also stain the teeth and tongue. Note that this is with prolonged use. Not some rinses if you get a canker sore.
So my advice to you and my theory because of the typical nature of BJJ is that your lesions can't be stopped and that they possibly grow larger due to bacterial infection, but most likely you can cut some of the healing time and to a certain extent cool the pain by rinsing with mouthwash containing chlorhexidine. (Like Corsodyl).
Any other remedies I'm not aware of. The good news is that canker sores always heal on their own. The bad news is that relief is scarce and that there are about as many methods to deal with it as there are people.
I hope the chlorhexidine thing helps you out. It certainly did for me. It's cut the healing time at least in half if not more.
Good luck!
