It is definitely one of my symptoms and I assume it refers to the sensation of walking on a sea of hard, roundish objects. Walking on large pebbles, or in our house, Legos, would also be an adequate description. I repeatedly check my shoes for foreign objects, even though I know the sensation comes from my feet. I have been known to look for dents. The maddening thing is, if I were to really step on a Lego or a piece of glass, and even cut myself badly, I would feel absolutely nothing.
It has nothing to do with the kind of shoes I am wearing, either. I have tried everything and I still experience the feeling, even barefoot or in socks.
I do think it is worse if I have been doing a lot of walking, although other symptoms, like the pain in my thighs and hips, seem to be relieved somewhat by walking. I never seem to be able to find the perfect balance point and the pain levels are different every day.