Hi, You will need to take B complex vitamin supplements as a deficiency of these vitamins can cause oral ulcers. Please also avoid hot and spicy food items till these ulcers heal. Use an antimicrobial mouthwash like chlorhexidine two to three times a day to prevent infection. Mouth ulcer gels are also available over the counter and provide pain relief by forming a coating over the ulcer. Sucking hydrocortisone lozenges three to four times a day also helps. Please avoid constipation as it too can worsen mouth ulcers. Best wishes.