You have to consult with Ear,Nose & Throat ( ENT) specialist for this problem.
You have not mentioned that U have any addiction of Tobacco/Gutkha chewing.
If You have addiction then It is time to quit by any means.
You have to stop eating Spicy & Sour foods untill consultation.
Please Purchase ORASORE gel or any other gel for mouth ulcer
You might by asked for biopsy
if Specialist concern.
Then don't worry. Go & check.
and GET WELL AS BEFORE.
-- DR JIGNESH