Try taking Acid-A-Cal and Apple Cider Vinegar capsules for a few weeks and see if that helps. I have bad sitting posture and started developing a bone spur on the back of my right foot. It was an unsightly devil's thorn and caused pain on my foot. I googled vigorously and found some natural remedies, started taking Apple Cider Vinegar and Acid-A-Cal pills twice every day. In 3 days, the pain was gone, and the bone spur completely disappeared in one week. I am still amazed! There are many other recommendations on http://www.earthclinic.com/CURES/heel_spur.html#.
Check them out. I buy my supplements from iherb.com. They are cheap and fast.