Foot injury

so my foot is sore. it is sore around the bottom of the ankle and around the top of the foot where it connects to the leg.

it got sore doing a tempo run. i had to cut it short. the day before i had done a long run (longer than it should have been), and day before had done a short duathlon 1.8k run, 10 k bike, 1.8 k run. i was wearing my ds trainers during my tempo run (i wear kayanos on longer non speed oriented runs).

is this likely to be cos my foot isnt strong enough?