Get Out the Styptic Pencil
Another way to get relief in the interim is to use a styptic pencil. Many a barber has used a styptic pencil to stem bleeding from minor nicks and cuts. Used on a canker sore, it will numb the nerve endings, temporarily reducing the pain.
Wield that toothbrush extra carefully to avoid irritating a canker sore before and after you've applied a remedy.