Plantar Issues

I was hoping this issue would shake itself out over time, but after my most recent run, it's flaming up again. My heel pain is the worst in the morning but gets better throughout the day to the point which I feel no pain at all while running. Of course this is making me a bit nervous since I have my half-marathon coming up on Saturday. Upon self-diagnosis I think it's Plantar Faciitis which I understand to be an inflamation of the connecting tendons of your heel. Wikipedia Link for more info. I could be wrong, it could just be irritation. I plan on running my half-marathon using smaller but quicker strides, hopefully placing less stress on the heels. Let me know what you guys think.