I had the same issue last week. I realized I had not had a bowel movement in over a week. Any possibility you are constipated.
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Active in the home is absolutely no substitute for general exercise which we all NEED! swelling has many causes, far too numerous to mention here.
If the swelling came after the walk to the store, it was caused by the awakening of normally unused nerves/muscles. Elevate the feet to same level as your heart for at least 30 mins every 6 hrs. But dont let it lapse back into hibernation, take a daily walk, slowly at first and increasing to a brisk one over a month, and keep it up then, you will feel the difference.