Canker sores in your mouth are caused by a variety of things.
The most common causes of canker sores though are vitamin deficiencies, disorders of the autoimmune system, stress, hormones and even injuries to the mouth such as accidentally biting the inside of your mouth when eating something.
Canker sores can also be brought on by spicy or acidic foods.
Cankers sores are not the same thing as a cold sore. A canker sore develops in the mouth while a cold sore which is caused by the herpes simplex virus develops on the lips or near your nostrils as a blister.
If you have a canker sore in your mouth you can get rid of the canker sore by gargling some apple cider vinegar since apple cider vinegar contains antibacterial properties which will kill off the bacteria in your mouth and help the canker sore go away.
You can also apply some orajel or other numbing agent to the canker sore to get the canker sore to go away.
A canker sore should heal within 2 to 3 weeks without treatment.