Its called raynauds (not sure if its spelled correctly) syndrom. It can be caused by frostbite. I used to get it really bad but it has got better. I have it on that same finger. Something to do with the blood vessels.

 wow you squeezed your hand! i remember doing that in the second grade

 no man i dunno i went outside with my dog for a run and then when i come back it goes like that its like 13 celcius outside i think im sensible to cold

 http://www.medic8.com/healthguide/articles/raynauds.html

 so then wouldnt ur whole hand be like that then?????

 it may be for strees,i live under terrible amount of it

 wtf?