Back of foot in pain?

if you think you've injured it you should get to a "foot doctor" or podiatrist (not pediatrist) sometime soon. since its only been two days maybe you should wait till its been like 5 days if the pain is still there then make an appointment. its certainly possible that you just extended some muscles without even knowing it, but it also could be something needing medical treatment or diagnosis such as carpel tunnel (yes they have a foot version of that.)