Having been a long time sufferer of mouth ulcers in which they lasted for 3-5wks and often so bad, eating and talking were almost impossible I seem to have found "my" cure, and I hope it can help someone else. Simply chew and "let soak" with crystalline ginger 3-4 times a day. If you catch them early enough, they just seem to fade away. I haven't tried any other variations such as ginger tea because I like the eating the ginger.
I placed a slice of ginger root on my canker sore. It relieves pain temporarily. I suggest before you eat something leave it in for about a minute. The pain usually goes away for about a good 45 minutes. My canker sore was so large it was swollen, bleeding, and also had pus coming out of it. I could barely talk. The ginger root allowed me to eat a meal.
Use a very thin slice of fresh cut Ginger Root to heal painful mouth sores. Rub the Ginger Root on the sore. Discard the slice after use, or eat it. Works fast, and kills the pain instantly. I have had a few mouth sores in the last several years and this treatment has worked 100% of the time, for me, with just one application.