Lump on pinky side of wrist...what is it?

I have a large lump on the pinky side of my wrist about an inch down. The lump itself doesn't hurt but my wrist does when I put pressure down on it. It's about the size of a nickle and kinda squishy. Yes, I know I should see my doctor and I will call him tomorrow, but in the meantime, does anyone know what this could be?