I Am A 80 Year Old Female In Good Health.

I am a 80 year old female in good health. Just took a wellness exam last week with very good results. I am very active, play tennis, weight is 120#, 5' 3", normal blood pressure , etc. I have one problem which so far my doctors have not been able to pinpoint nor diagnose. That is, I have feeling of numbness in lower legs along with visible surface skin red spots or blotches on my skin on top of feet and lower legs. I do not have neuropathy. What are possible causes?