58 yr. old male , no health problems,5 11 200 lbs. walk 4-5 miles per 3-5 times per week, standing at work 9 hrs. per day. Have large light colored bruise showed up behind left knee , 4-5 months ago, no pain, no discomfort. Now have another similar area, redder, behind right knee.both below the knee, top of the calf . what gives???