How do I get rid of a canker sore?

I got these stupid things before but usually there gone within 2 days or just one day. The one I have now, i've had for a week and it hasn't got better? Is there anyway to get rid of it, a non painful way? I've tried mouthwash but that burned like hell. I cant brush my teeth that good on the side of my mouth its on, i have to eat on one side of my mouth and drink out of a straw, because even water makes it hurt a lot. Is there any non painful way of getting rid of it?