I'm pretty sure that I have either plantar fasciitis or achilles tendonitis. My first step in the morning is painful with the pain reducing thereafter, which I know is a classic PF symptom. However, the pain is in my heel - in the area just "up" from the bottom of my foot. It can be on either side of my heel but definitely not on the bottom.
I exercise regularly, but haven't significantly increased my workouts and I'm not doing anything crazy. I play tennis once or twice a week. Similarly once or twice a week, I'll run on a treadmill at the gym for two miles. Other days, I'll use the bike or eliptical machine (today, for instance, I did one mile in 8:00 followed by 30 minutes on a recumbant bike). Once or twice a week, I do weights, half of the time focusing on lower body (squats, lunges, toe lifts, reverse toe lifts seem the most relevant to this question).
How do I determine which issue it is? For the PF, I know that I want to stretch the plantar fascia, calf, and achilles if it's PF. But if it's AT, I want to allow the achilles to rest and repair itself.