your problem can have multiple causes. if it is due to tobacco use in any form, you need to get it checked as soon as possible by a dentist. if it is due to gastric upset, you need to see a gastroenterologist to check if you have gastric ulcers. most commonly it is due to improper diet and high stress, which should get resolved with multivitamins and lot of water and bland food. I would recommend to get a long standing ulcer checked.