Symptoms that may indicate that you have a canker sore:
- a painful sore or sores inside your mouth, on the tongue, soft palate (back portion of the roof of your mouth), or inside your cheeks
- a tingling or burning sensation prior to the appearance of the sores - sores in your mouth that are round, white, or gray in color, with a red edge or border
And in severe canker sore cases, you may also experience:
- fever, physical sluggishness, and swollen lymph nodes