Thanks for your input. I agree that it doesn't sound like a sprain or PF. Since you last posted I've been doing SMR around my calves, working around the extensor/flexor hallucis longus areas as you suggested, as well as doing some deep massage in the sole of my foot. I found some tender areas in both my calf and foot that coincide with trigger points that are reportedly related to pain in the area I am getting it. Since I've been doing all of this work the pain has become less severe and is occuring less frequently so hopefully this will solve it.