Heel pain - not plantar - any ideas?

Non-runner

So about six months ago I developed a bit of a niggle in my right heel, underneath.  I can pinpoint the exact spot.  Got worse, stopped running and walked, got worse and now hurts all the time.  Five months run-free and can now only bear the pain for three miles walking.  It feels like a nail being driven into the centre of my heel.  Podiatrist went through most things and did the usual, plantar stretches, ice etc.  Finally referred to NHS, X rays came back clear (as predicted by the podiatrist who said it would need an MRI as it is some sort of odema in the bone).  So currently waiting for my next GP appointment, three weeks away, when I will no doubt be referred for another scan, then another three week wait for an appointment to be referred for another scan etc.  If I didn’t have my bike I would be pretty depressed.  Has anyone had anything similar and any suggestions? Cheers.