These are little bones in your foot. There are five in each digit.
"How To Address Metatarsal Stress Fractures
Metatarsal stress fractures do affect ballet dancers, but the most common one you’ll see is at the base of the second metatarsal. As with many stress fractures, it is often difficult to see these injuries on the X-ray film, especially within a week or so of the onset of the symptoms. Persistent tenderness in the proximal first web space or around the base of the second metatarsal in a dancer usually indicates a stress fracture until proven otherwise.
This condition is usually an indication for a bone scan. However, if the dancer is very young, you would simply instruct her or him to refrain from jumping and doing grand pliés until the pain and tenderness are gone. You usually don’t have to put this fracture in a plaster cast. Activity modification for six to eight weeks is usually sufficient for the fracture to heal providing the dancer has not been working on it for a prolonged period of time while it was hurting. If she or he has, it will probably take longer to heal.
The most common acute fracture you’ll see among dancers is the spiral fracture of the distal one-third of the fifth metatarsal, also known as the “dancer’s fracture.” Dancers sustain this fracture when they lose their balance while on demi-pointe and roll over the outer border of the foot.
If it’s a displaced fracture, it may be necessary to put the dancer in a walking cast for four to six weeks while it heals. (One can accept a considerable amount of displacement with this fracture.) In fractures that are minimally displaced, it is often sufficient to emphasize a comfortable running shoe and restricted activities until the fracture heals. This approach will allow dancers to swim and stay in shape while they are waiting to dance again. Occasionally, you may see a markedly displaced and comminuted fracture. In this case, performing reduction and internal fixation will be necessary."
This is an obvious injury of a fracture of any bone out of 25 pieces in your foot. It is a marvel to know there are 50 pieces enabling you to do all those fancy moves. Fracture occurs when maximum presssure is applied and you go over a tipping point. Basically you will feel this one and will require you a cast and rehab.