This may sound a bit far-fetched, but it's worth a try. I had serious pain in my feet 5 years ago and someone suggested magnetic insoles for my shoes. I laughed at the idea, but tried it. It worked far better than I thought possible.

It might be worth looking into for your problem. A medical supply shop should be able to get the insoles for you. They run approx. $75/pair here in Canada, but are well worth the money.