If it hurst in the middle you could have a stress fracture on the metatarsals.
If it hurts medial (inside) then you could've sprained your deltoid tendon. Lateral (outside) your ATF, CF, and CTF could be sprained.
and if its your arch you could've sprained that.
hope this helps.
you should get checked out... i always wear an ankle brace, or get my ankles taped up