What's the trouble here? Is it just tightness perhaps? You can work on the arch area with a tennis or lacrosse ball if it needs loosening up a bit.
Almost exactly a year ago I ran a three hour race in Arizona with a new ankle brace and completely messed up the arch of my foot. The doctors never really gave me a diagnosis, in fact the doctor who saw me in Arizona said I was overreacting. I had to be on crutches/in a wheelchair for a few days. Ever since then I have random (actually, relatively predictable) plantar fasciitis-like pain in the sole of my foot. You're right, working on the area with a ball helps, as does stretching my calves.