This sounds like Raynaud's Phenomenon. It's a vascular condition that causes swelling and discoloration of the extremities. Cold temperatures usually trigger it.
Raynaud's disease is idiopathic, meaning there is no known cause. Raynaud's syndrome, on the other hand, is usually caused by autoimmune diseases such as lupus or multiple sclerosis.
Do you have a family history of any autoimmune diseases? Raynaud's syndrome can sometimes be the first symptom of autoimmune diseases. If you have been feeling a little off (i.e. fatigued) it may be worth a trip to the doctor. You will probably get a referral to a Rheumatologist.
In the mean time, it's nothing to be worried about. It can go along with autoimmune diseases, but not necessarily. To avoid it, make sure you wear gloves to keep your hands warm in cold weather. If you smoke, stop now as smoking can trigger it. When you are having an attack, put your hands in slightly warm (not hot) water and gently massage your fingertips. If you do not have access to warm water, sit on your hands. Sounds silly, but it helps restore warmth to your fingers.
I suffer from Raynaud's.