Yes calcaneus is the answer...
Revision:
I am down, way down
Yet I still support you no matter who you are
I am often neglected
But I am protected
I don't like people who have too much weight
It causes me distress
But if you don't care
I can give you a great deal of pain
I have a friend on top of me
I have more friends in front of me
I have no friends behind me
What am I? 
It's the lowest bone in the body, so to speak, and it supports the
whole body weight, often neglected because people wear all sorts of
ill fitting shoes and cause bony spurs formation (more common in
obese and overweight patients) and then leads to severe amount of
pain. The talus is the friend on top of calcaneus, the navicular,
the 3 cuneiforms and cuboid are friends in front of it, but it
doesn't have any friends at the back...
