The brownish discoloration over your bilateral lower leg could be due to two conditions
1)Venous stasis pigmentation which is seen in venous insufficiency
and varicose veins
or progressive pigmented purpuric dermatosis
. A benign condition characterised by red brown spots over lower legs and seen usually in people with prolonged standing hours.
As both the diseases require proper history and clinical examination, I would advise you to visit a dermatologist
so that a proper diagnosis based treatment could be offered.