What Causes Discoloration Of Arm On Application Of Pressure?

Hello - when I have my right arm bent when I shave or if I m sleeping on my left side with my right arm bent on my right side, my arm from where my bicep meets the inside of where it bends down to my forearm swells and turns a darker color like I m giving blood with rubber around my arm. I m 6 1 225 125/85 BP, 128 triglycerides, not diabetic, kidneys, liver, are all good. In good shape, don t smoke and occasionally have a Bud Light a couple times a month. I drink 3 liters of water a day, take calcium, multi vitamin and fish oil.