For mouth ulcers, dab 100% pure lavender essential oil. I was bothered by a painful ulcer for 10 days. Bonjela and Difflam Mouth Gel did not help. I was advised to apply salt but no way was I going to subject myself to more suffering. My colleague suggested lavender oil. I happened to have a bottle of Young Living lavender oil but any reputable brand will do. It goes on painlessly but the taste isn’t great. The effects were almost immediate and the ulcer was gone in two days.