Mouth Ulcers can be of various types and for various reasons. They could range from simple single apthous uclers to herpetiform ulcers. First visit a dentist so that we can single out the cause and then treat it effectively.
Next Steps
Visit a dentist for local examination. For time being relief use a topical anaesthetic like dentogel
Health Tips
Do get a detailed history of any kind of drugs, diseases or related past.