I'm still following the Nike+ Coach program and ran my 4 miles today on the treadmill. I even did the last mile at a 10 minute mile pace.
My right foot has been swelling but it doesn't hurt while I am running. It does hurt when I stop though. I considered going to the clinic until I found out that they don't take my insurance. I figure all they will say is to stay off of it regardless of whether it involves a strain, sprain, tendonitis, stress fracture, or some other injury frequently encountered by runners. So I guess it really doesn't matter what they might have found, the treatment is still the same. Stay off of it, which I don't plan to do anyway!
I suspect it isn't anything too serious.