Achilles, ankle or heel problem?

Iron Ant

I've started getting a problem in the heal/achilles area of my right foot. The pain seems to be around the boney area where the achilles ends at my heel (about an inch up the back of the heal). The pain seems to be worst after a couple hours of driving but I can still run although it doesn't feel quite right. The thing is I don't feel anything wrong with it first thing in a morning like I've seen posted for the usual type of achilles problem.

Any suggestions what I might have done would be great.

thanks