Pain from a canker sore generally lessens in a few days and the sores usually heal without treatment
in about a week or two. Avoid spicy or acidic foods during this time. You can
use topical ointments like numbing ointments, such as benzocaine , anti-inflammatory (steroid) gels, benadryl allergy liquid mouthwash, oral preparations of steroids and vitamin supplements.
But if the sores last for more than 3 wks or start spreading then please consult a dermatologist.