Reasons for canker sore are not well understood.A diet lacking in
vitamin B-12, zinc, folate (folic acid) or iron, An allergic response to certain bacteria in your mouth, Helicobacter pylori, the same bacteria that cause peptic ulcers could also play some role.Drink adequate water ,take vitamin b complex tablets daily and apply Tess buccal paste 3 times daily.You can also consider taking tab rebamipide 100 mg twice daily for 7 days.