If top of my foot is sore. how do i know if it's a sprain?

Did you injure it?: If you sprained/strained your foot, that could very likely be the cause. There are many possible reasons for foot pain, so if there is no history of an injury or overuse see a podiatrist.

Usually trauma or: Overuse cause a sprain. The events leading up to the soreness would help with the diagnosis. Your doctor can determine this. X-rays or other diagnostic techniques may be used if there is any uncertainty.