I have a lump on the ball of my foot. It's very painful, and about the size of a small marble, sometimes very red and swells even more than it is. Has been growing about 6 months. I have no insurance so doing anything with it now is not possible. Could this possibly be some kind of cancer?[size=3]

Is their difference in temperature with the rest of your skin? Go to an Emergency room or free clinic. Loosing a foot or your life will be harder to pay for.