Painful spots on hands?

sometimes i get these painfull small pressure points under my skin at the fingertips and in the palm of my hands. They only last a day, and its under the skin... what are they? I used to think it was from dramatic temp. change.. but they're ittitating and I want to know what's causing them so i can prevent them. I dont get them often, but enough to annoy me and make me ask this question....again...