This may sound ridiculous.I have not told anyone about this.When I walk for more than 10 or 15 minutes I get a feeling that I am losing the feeling in my legs.I need to force my efforts to carry on a little further,until I lose my power to walk completely,as if I can't feel my legs.I discovered that if I turn around and walk backwards for a couple of minutes then I can suddenly walk forwards for a few feet further.I am not tired when I walk and I am fit in every other way.I get scared that I am about to lose the feelings in my legs for good.