I have had problems with canker sores in the past. In my body they seemed to be connected with yeast. I have not had one in a long time but if I did I would try applying Nancy's whey because it stopped a yeast problem with my eyelid. Several months back, my left eye lid was red, swollen, itching, burning, and peeling. After tying many remedies, I applied whey and the relief was very quick. It took about a month to totally get rid of the problem. It has also helped a friend of mine who has Rosacea.
I wonder if pulling with a different oil might sooth the area.