In a quick look-see about what a stone bruise is, I found that the best way to treat it is probably just to massage the area for a bit every day... To get the blood flowing around the area and the damaged cells to clear out.
I also saw that it could be "metatarsalgia, which is like a "toothache" of the metatarsal head at the bottom of the foot. Sometimes there is swelling at the area of tenderness but usually there is no discoloration. Pressing on that metatarsal head at the ball of the foot is tender. Pulling up on the toes, dorsiflexing them, can also cause symptoms as this stretches the capsule and soft tissue at the bottom of the joint, causing discomfort.
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What often starts the symptoms of the metatarsalgia can be wearing a pair of shoes that are too old or worn where the midsole has bottomed out, a stiff shoe, overstriding, hard surfaces, or overtraining.
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Using a cushioning innersole, and sometimes a metatarsal pad, can be useful also in taking the pressure off the area. It is important to avoid going barefoot or walking around in slippers/socks. Icing the area for 10-15 minutes can help with the acute inflammation as can oral antiinflammatories."
from
http://www.aapsm.org/ct0698.html