I have suffered from canker sores for a most of my life. I am 35 and it took me years to figure it out. One thing to avoid (may sound strange but...) is putting your fingers in your mouth when using or working with paper/books/carbonless forms. I am an Accountant and found myself wetting a finger here and there to get throug paper work quickly. I now use a rubber finger cover and it has cut down on the sores very much. I also noticed that a week prior to my period I would get several in my mouth. Red/white and painful. I would sometimes get upto 7 at one time. Hope this helps..... email me with any questions.