How can I brush when it hurts?

I have a canker sore that seems to wanna stay.. Until its gone how can I brush my teeth when even the toothpaste makes it hurt... A LOT. Im a 13 year old kid and I NEED to brush!! Should I numb my mouth with some canker sore stuff that numbs it for a few minutes? PLEASE HELP!! Thanks! Also anything for eating? Sometimes it hurts to much I cant...