Soreness Under the Ball of the Big Toe
(Bruised or broken sesamoids) Description:
Tiny bones called sesamoids are located under the ball of your big toe (where the toe connects to your foot). These bones sometimes bruise -- it's a hassle, but it's also a warning system; they start aching before you damage the bones of your big toe. To see if you've bruised these little guys, press hard on the head of your big toe with your thumb. If you're howling in pain, that pretty much confirms that you've bruised, maybe even broken, your sesamoids.
Likely Causes:
Increased mileage, maybe new hillwork or speedwork. Whatever the cause, you are running too much on the balls of your feet. Also, it is possible that your running surface is responsible -- too much hard pavement. A final possibility is that you are doing nothing wrong at all, but you may have been betrayed by your own bone structure (i.e. you have bony feet without much fat padding).
Remedy:
Ice your foot, putting it on ice for ten minutes, off for ten minutes, and repeat. Do this often, maybe four times per day. This, of course, only treats the symptoms. You also have to treat the root cause and stop pounding the balls of your feet into pulp. Reduce hillwork and speedwork, and also take a look at your stride. Your heel should hit the ground first, rolling through the middle of your foot and then springing off from your toes. You should not be landing on the balls of your feet.
The problem can further be avoided in the future by padding around the ball of your foot to take pressure off of it. Get a piece of felt or foam rubber (try using a Dr. Scholl's heel pad, for example). It should be 1/4" thick and about 2" square. Cut a shallow "U" out of the pad so that it fits snugly behind (not over) the ball of your foot. Behind, incidentally, means on the heel side, not the toe side. The pad should fit right behind the painful area. You'll know you've got it right when you try it out and walk around -- the pressure will be off the bone, and the pain will be far reduced. Tape the padding to your foot and wear it in your daytime shoes as well as your running shoes.
You should be able to hit the road immediately, and the pain will likely disappear in about two weeks. If it does not, you may need custom orthotics. See a podiatrist, preferably one who is also a runner.