Three separate times I have had just one finger cramp and hurt. An area slightly smaller than a dime at the base of my finger will turn bluish/purple. It appears to be a spasm of the arteriole. Just today I had another episode this time on the ball of the foot beneath the big toe. Four hours later and the area feels okay but it is colored reddish as if bruised, but it is not. I was not out in the cold but have been under a lot of stress.