Rinse your mouth out with Piroxide. Not the greatest tasting way to go, but it'll work as well if not better than anything on the market in terms of getting rid of the sore in a timely manner. That being said, nothing is going to clear it up completely except time. Even the over-priced stuff made for canker sores only numb for a short period of time.
Used to get canker sores ALL THE TIME! Through process of elimination, I discovered I was alergic to chocolate. Stopped eating chocolate, and the canker sores that were almost constant vanished and haven't come back in years.