This is a stress fracture of the second (or sometimes third) metatarsal. Youll feel pain in the middle of the long bone(s) of your foot, which will slowly increase with distance, reaching a crescendo as you end your run. The pain will return earlier during the next session and become severe sooner, forcing a premature finish. This pattern will continue.
You may be able to feel or see a little swelling around an established stress fracture, though an early one may simply be painful if stressed by pressure, or when you move the fractured halves in opposition to each other.
When pain alone is the symptom, a bone scan may be the only way to convince the athlete that a stress fracture exists. X-rays will show healing callus in an injury which is more than four weeks old, while doubters may respond to ultrasound testing by a physiotherapist it causes real discomfort if positive!
What else could it be?
Few injuries show crescendo pain apart from a stress fracture. Muscle injuries and strains may occur between the bones, but you can often run with them, unlike a stress fracture.
Rest! You may be able to swim or cycle as long as it doesnt provoke pain, but running which caused the injury is out.
This is as much psychological as physical you need constant reassurance that time (probably about six weeks) will heal the injury. A plaster cast is rarely required. Biomechanical gait analysis may prevent further injury, though recurrence of a stress fracture at the original site is very uncommon.
Can you run through it?
No. Full stop.
Five per cent of stress fractures fail to heal as expected and some form of malunion occurs. A very small percentage need bone grafting.