I Have A 93 Year Old Neighbor Who Is Having

I have a 93 year old neighbor who is having weakness in his legs (when he has always been very strong). Was wondering what could be causing this? Could it be Vitamin D deficiency, iron deficiency, or something like that. Also, both of his lower legs are very red up and down the shin bone. One leg worse than the other (redder) with white flaking going on. Any ideas?