Hi, Thanks for posting the query, Canker sores mainly occurs due to physical or chemical trauma, ulcerations can be due to trauma, nutritional deficiency, hormonal imbalance. I would suggest you to get a checkup done once. Take multivitamin suplements, tab vitcofol. Apply hexigel oral ointemnt topically over it. Maintain a good oral hygiene. Take care! Dr Qazi Ammara.