What the Heel?!

What the hell is with my heel?  I am experiencing a lot of pain in my left heel.  Not exactly sure what I have done to it but it hurts.  I sleep with a brace on it and that tends to help and the day starts off fairly well but after a while it starts to throb.  I was foot racing Jack a couple of weeks ago and was wearing my work shoes.  All I can figure is that I injured the foot through impact while running.  I do my best not to let it slow me down and it really hasn't.  It is just a matter of enduring the pain and carrying on.  I've got to figure it out though as a good long hike might be out of the question and short hikes will require some recovery time.  Hoping whatever is the matter will heal itself, soon.