A mouth ulcer that does not heal after two weeks requires urgent evaluation by a dentist or doctor. Please do not try further self-medication. Persistent ulcers can indicate underlying health issues, including severe nutritional deficiencies, autoimmune conditions, or, in rare cases, oral cancer, which may require a biopsy to diagnose. Avoid spicy, acidic, or hot foods that irritate the ulcer. Your priority should be getting a professional examination to find the exact cause and receive targeted prescription therapy. Please schedule an appointment with a healthcare provider as soon as possible.