You need to find out the exact cause for your cancre sores. Though recurrant ulcers may indicate a hepes simplex infection, it is not uncommon in elevated stress levels, in patients with a family history of the same, with IBS (Irritable Bowel Syndrome, especially Crohn s disease and GERD), some Anaemias and Leukaemias, & as a reaction to certain antibiotics like Penicillins (rare) and a variety of other irritants which include citrus fruits and even toothpaste sometimes. A proper investigation to establish the exact cause of your ailment is thus needed to find a proper cure, so please visit a good Dentist, or an ENT specialist to start up on investigations. Also, you need to take a few precautions: 1. Do not take stressess, or tensions 2. Drink lots of water. 3. B-complex therapy with Zinc & Antioxidants will help. 4. Do not consume spicy foods (eat bland foods) and citrus fruits, and include a lot of curd & buttermilk in your diet. 5. Check the contents your toothpaste, & if it contains sodium dodecyl sulfate (better known as sodium lauryl sulfate; acronyms: sds or sls), then change it, You may be allergic. 6. Very rarely, (as studies are not well established, so not much known), people develop an allergy to Cow s milk, which can cause oral cancres. 7. If your mouthwash helps, keep using it.