Wow, I have the same probelm for 2 weeks now. It seems to be healing very slowly even when I didn't bike for a while. I'm suspecting it is a sore anterior tibialis tendon. I believe it is that because it hurts only between the first and second metatarsal which is the middle bone of the first and second toe. It also hurts slightly when you press on it but not if you press towards the outside of my right foot. It conerns me as well and hope it goes away soon so I can resume biking.