Round knot on the bottom of my foot?

There's a knot the size of a golf ball on the bottom of my right foot. On a scale of 1-10 ten being the most painful, it's a 10+. I've tried ice and heat pads but both of them just irritate the spot more. It's a firey red color. Every time I apply any pressure on it, it gets redder and more painful. I don't know what this is or why I have it. I don't think I'll be able to drive myself to work in the morning that's how bad it hurts. As I'm laying in bed now and not moving my foot it's contantly throbbing. Anybody know what this is and how I can get rid of it. I'm not off until Friday so I plan to go the doctor that day. I'm trying to hold off until Friday but if the pain doesn't stop I'm going to have to take a trip to the ER.