Mid-foot pain is an uncommon problem. When it does occur, it's often caused by either a short first (big) toe or a long second toe. This is called Morton's toe. Sports activities like track and field can put pressure through the longer toe into the metatarsal-tarsal joint. That's where the long toe bone meets the bones of the ankle.

When your son pushes off with his foot, he jams the bones of that second toe. Whether it's because the first toe is short or the second toe is long may not really matter unless surgery is planned.

However, to answer this question a recent study was done at the University of Washington in Seattle. They used X-rays and CT scans on patients with midfoot pain and Morton's toe to find out which toe is the real problem. They found that adults with mid-foot pain had BOTH a short first toe and a long second toe.