What Causes Dark Discoloration Around Bottom Of Leg?

hi, my partner has very dark discoloration around tha bottom of his legs which get infections..i dont no to much about this as he hides it from me and wont go to the doctor..should i be worried and get him to seek help? he is 49 and has had it 4 a very long time although now he's starting to cough n wheeze, bleeding nose n general weakness. Does not drink or smoke, very healthy lifestyle.