i had the same problem with my thumb and 2 fingers next to it. it was caused by a blood clot. they dissolved the clot and the two fingers cleared up rapidly but the thumb hasn't cleared up yet. i will have to go back to be checked for another clot or possibly gangerine.
thumb is discolored and swelled. very painful to touch or put in warm water. it turns black when i put it in warm water. started about three weeks ago with swelling and discoloring. it looks like a bruise on the bottom side up toward the outside tip and is swelled from the bottom crease at the joint up to the tip. i have sever pain when i press it against something or try to use it. sever pain when in warm water and turns black. it doesn't hurt to bend it and i didn't sprain or smash it. it is always cold from the knuckle to the tip and feels numb most of the time until i try to use it or push on it. thank you