What should i do if i have this annoying canker sore?

Usually resolve on : Their own. If you have a canker sore ( aphthous ulcer) you can rinse your mouth w warm salt water. Mix a teaspoon of salt in 8 oz of warm water – gargle w this several times a day. Another option is to swish a mix of 1 part milk of magnesia ; 1 part liquid Benadryl (diphenhydramine) in your mouth. Spit out after about a minute. Avoid eating spicy food or food that is hot (high temperature). Please call your dentist.