Do get the tooth paste mentioned in a previous post or you can try Rembrants version, cannot recall the exact name but it says something on the packaging about being anti cancer sore. I started using only SLS free tooth pastes about 8 years ago after hearing Paul Harvey mention the Rembrant stuff on one of his broadcasts. I had spent the majority of my life either with canker sores, as in 24/7/365. Mine did not heal within a week, they lasted for weeks and weeks. They were often the size of quarters and so painful that it was difficult to speak or eat. I tried L-lisine, which helped a bit, but until I changed tooth paste I was still plagued with them contantly. Besides changing tooth pastes I also NEVER eat walnuts and rarely eat pecans. When I was still eating such things I would from time to time attempt to eat a cookie or brownie with walnuts in them, just spit the walnut out-no harm, right? Wrong! I would have canker sores on the tip of my tongue and anywhere on the inside of my mouth that the walnut spent any time on. I also became very aware of some of the multi grain breads which sometimes have walnuts in them. Again, do try the toothpaste change. I bet it will help a bunch.