The run clearly aggravated the sprain in the foot. The good news is that while one never knows for sure until they see a doctor (and even then...), I don't have any doubt now that this is just a foot sprain (extensor tendon on top of foot). And with proper rest, they apparently do heal nicely.
The bad news is that I'll probably have to take a couple of weeks off. Frustrating, especially with the spring weather, but last week I saw dramatic improvement after four days off. Had I have waited a bit longer I probably would have had it healed up by now. But runners do stupid things with injuries and yesterday wasn't too smart, but keeping the glass half full it did provide good information and helped to clearly set the course on what to do next.