Brown arm bruising

Two dime size brown bruise marks showed up on the inside of my lower left arm. They had been there about 3-4 days when a quarter size bruise showed up on the top side of my lower left arm. I did not hit it on anything. They do not hurt like a bruise but look like a bruise would look after it had faded from the red-purple color. I do have the normal aging brown and white spots on both arms, but these are totally different.