Secondly the tendon in your heel may have been stressed so give a good deal of rest for a few days/weeks.
Thirdly you may have a small bone protrusion in the heel, which will find a place for itself in a few weeks time and the pain will stop.
Fourthly if there is any swelling in the heel you may like to check for any stress fracture due to running on hard surfaces, without realising it. So get an Xray done, you don't need a CT scan.
Lastly try this home remedy:
Take hot water, add salt, turmeric and neem leaves and dips your feet in them for a few minutes at a time and continue for a few days. It may relieve the pain.
I was an athlete too, with multiple interests in basketball, football, squash racquet, during my younger days and this is based on my experience as an athlete, however this is not to be treated as medical advice and may consider it accordingly. more
Thank you so much for your valuable advice and suggestions. Instead of running, I am using stationary bicycle currently to reduce pressure on my feet. HbA1c is normal. Neem is not available here. Using salt and turmeric for soaking the feet.
Hope I feel better for my next marathon, which is on March 7. more