That “mystery bump” on the outside of your foot might not be what you think Hi, Dr. Pelto here. I recently treated a patient with a bursa under the fifth metatarsal head. This is the bone along the outer edge of your foot that takes pressure during walking. She came in with a noticeable bump on the bottom of her foot. At first glance it looked like a simple pressure spot, but when we performed an ultrasound, we found a large fluid filled bursa sitting right beneath the fifth metatarsal head. Her