Fibula.

Right. Never felt any pain in my lower. My foot felt funny during the run for a portion. Something odd, not necessarily painful but certainly a touch uncomfortable. Never felt anything like it before and I only felt it in the ball of my left foot.

Hmmm...this really hits home for me. I had a big Sat/Sun race scheduled for the end of May. Got some carbon-plated supershoes - ran with them 5-6x on the road, on the track, doing hill repeats. All good. Sat race - no problem. Sun race, after (hours later), I had a bit of soreness above my ankle on outside of my leg. Weird place for soreness, went away. Raced two weeks later (all of these races are sprint distance duathhons, so about 10K running per race). Pain started part way though 2nd run. Was limping at the finish. Stress fracture diagnosed a few days later, a few cm above the ankle in the fibula. Never had anything remotely like this injury. Supershoe-induced? Who knows, but use of the shoe, racing and the injury are all correlated...