I've had major heel pain several times. One of the worst and it seems rather what you are describing was plantar fasciitis. Do a google for heel pain and it will be the first one up. Then once again I had another diagnosis of heel pain (but this time with a swollen ankle ). It was a stress fracture in my ankle.

Don't be so sure it's PN. I'd also suggest a good foot doctor. Mine has helped me many times.

Good luck,
Billye