When I Walk It Feels Like I Have Stumps That

When I walk it feels like I have stumps that I am trying to walk on, This doesn't start out this way in the morning but happens after I have been up walking around for a bit. This started a few days ago. I have bad knees and had surgery on my back 7 yrs ago for a bone that splintered and was cutting into my nerves, all fixed no more problems