Your problem seems to related to stress. Resulting in a condition called recurrent aphthous stomatitis. But there could be other reasons like trauma due to tongue, lip or cheek biting; viral infection like herpes.
Next Steps
Get your condition checked by a general physician or dentist. if it is a case of simple stomatitis, you'll be prescribed a pain relieving ointment and b-complex
vitamin supplements.
Health Tips
Get rid of stress. It lowers your immunity as well. Cortisol is the main culprit. Take a break from work. Go on a vacation.