I have dark bruising on both my arms from my elbow to my hand. I do gardening, and house hold chores, but sometimes really don t know what caused the blood to raise into a hives look, and itch like crazy, 24/7 for months. been to a skin specialist, who took biopsy s, which came back negative. I have lupus, with no problems, for 25 years. I checked my vitamin list for which ones could cause thinning blood. I take several prescription drugs. any ideas?