So, since my pain this morning was still pretty bad in my foot I decided to go to the hospital. An x-ray showed an obvious fracture. The doctor described it as a fracture common in soldiers called a "March Fracture".
I found a good post that described:
"Stress fractures often are the result of overuse or repeated impacts on a hard surface. Increasing the amount or intensity of an activity too rapidly is a common cause of a stress fracture, as is using improper equipment. Fatigue of the foot bone(s) caused by repeated overload, as with marching, walking, running or jogging."
This definitely sounds like something that has been caused by over doing it with my FiveFingers. I'm now forced to take 4 to 6 weeks off of training.
I've decided that my training for the race this summer will have to continue sans VFF. I'll need to pick up a new pair of trail shoes. I'm torn because I am no longer having knee problems but this is obviously a show stopper for the VFFs.