I Have Been Experiencing Some Numbness, Not Like My Foot

I have been experiencing some numbness, not like my foot has gone to sleep, but more like as if I have a calloused area. It is located on outer R foot in front of heel and last night it seemed to affect the little toe as well. I have noticed this numbness since January I believe. I am not diabetic. I had bilateral knee replacements in 2011 three months apart. I am not a runner, mostly sedentary.