Brief answer: Apthous Ulcer /Canker sore. Hi.. Can understand your concern.. As per your complain it seems you have a canker sore or an apthous ulcer which is characterized by small to oval ulcers which can be painful. They can have a grey white to yellowish appearance with red outline. The exact reason for the cause of this is unknown. It takes around 8 to 12 days for the ulcer to heal. You need not to worry as it is not cancerous and will heal without leaving any scar. What you can do is you can apply numbing gels like Mucopain gel or orabase gel or any other gel with other names containing either lignocaine or choline salicylate. These gels will numb the are and relieve the pain. If you apply it half an hour before taking food it can ease you while taking food. Use antimicrobial mouthwash to gargle. Do saline gargles. To relieve pain and inflammation Ibuprofen or paracetamol can be taken. You can apply mixture of 1:1 hydrogen peroxide and water over the sores. Avoid hot and spicy food. Take cool and soft diet. Drink plenty of water.. Hope it will relieve in a week or so. If the condition does not start improving or the sores increase in size consult a doctor to get evaluated for other conditions like herpetic infection or any allergy. Hope your query is solved. Thanks and regards.. Dr.Honey Nandwani Arora.