Mouth sores can be caused as an allergic reaction to something you are consuming or often also due to mental stress, or some medical condition. There could also be some local irritant in the mouth, like a sharp tooth edge. Firstly try and find out if you get them after eating or drinking something particular and avoid all spicy food. Take vitamin B12 with folic acid for a month and apply a soothing gel like hexigel on the ulcers. Also please visit a dentist... a proper diagnosis can be made only by checking clinically.

There are multiple reasons for recurrent mouth ulcers and the best diagnosis can be made only after a proper clinical examination and taking a detailed history from you. For temporary symptomatic relief you can apply anaesthetic ointments like dologel CT. Visit an oral pathologist or oral medicine specialist as soon as possible for the most accurate diagnosis. The right treatment can be instituted only after the right diagnosis.