I had my knee replaced in 2006. Like you, I had not had full function of my leg for many years prior to the replacement. I was a tad different in that I was unable to straighten my leg until after the surgery. I had not had my leg straight for the better part of a decade, and when I woke up from surgery, my leg was straightened out. The pain in my ligaments, muscles, and tendons was immense because I was stretching out parts of my body that hadn't been stretched that way in years.
I am not a medical professional, so it would be best to discuss this with your surgeon or provider, but it sounds like you may be experiencing something similar. I experienced swelling due to what sounds kind of similar to you – using ligaments, muscles and joints in a way they had not been used for many years. In my non-medical expertise opinion, it sounds like you might be stretching and working things that have not been used for many years, and they are responding by swelling.
I have end-stage arthritis in my right ankle and have been trying to refocus on walking heel to toe as well… it is harder than one would think isn't it?
@topdog11, other than your concerns with feet, how is your knee doing with bend and range-of-motion?