Re: help foot problem!
Possible that you tore your plantar fascia. I did that in the middle of a soccer game. I was back pedaling, then went to change direction, and when I pushed off I heard a crack (sounded like metal cleats on cement). I actually looked behind me because I thought I stepped on a rock, or someones foot, and then with my first step down I felt a stabbing sensation. The bottom of my foot turned black and couldnt really take any pressure for a few days. Stupid me kept playing without ever giving it much of a rest, and wound up partially tearing the post. tibial tendon, and had to be in a cast for 6 weeks.
The fact that curling your toes makes it more bearable definitely seems like it would be a big clue in figuring out whats wrong. If I were you I'd rest it and stay off it a few days... maybe use some crutches if you have them and ice it. If it doesn't feel better then, see a doctor.