Marion here had that, very painfully. (Mainly a result of working on hard floors with hard-soled footwear, but stuff like step-dancing didn't help). She went through umpteen different kinds of shoes and insoles, but the ones that REALLY made a big difference were a new kind of insole. These have air cushions under the foot (mainly just in front of the heel) connected by a tube to a reservoir of air round your ankle. The air gets pushed up into the reservoir as you put your weight down and then flows back when you lift your foot. The firm that makes these is Aircast, www.aircast.com. They last much better than you'd think from the odd design.

She now uses a variety of footwear and insoles - often using MBT shoes and sandals though they're helluvan expensive - but the Aircasts are the last resort when the problem threatens to come back seriously.