F=MA. A soccer ball doesn't have that much mass (to break your foot), and even if it was going really fast it wouldn't have enough acceleration. I doubt your foot is broken, but I would keep weigth off it if it hurts that bad, and keeping it cool tends to numb the pain. However, if you want it to heal itself, don't cool it. There's this epic thing called the human body which ought to take care of your foot if its' doing it's job well.