Are you scraping your tongue everyday?
I find this really helps and prevevents cancor sores from developing. You can buy tongue scraper or just use a tea spoon.
Also, when I brush my teeth I brush my tongue too.
If the sores persist try disolving a couple teaspoons of Sea Salt
in a little hot water and swish it around your mouth - spit it out but don't rinse for about thirty minutes.