Why am I so cold?

Of recent my hands have become very cold. I’ve also noticed that my skin (legs mostly- feet and knees, not the calf) are very cold. They appear reddish or pinkish and when you touch them they turn white, I takes a while for the skin to return to the normal color (the pinkish color).

I’ve been told this means I have poor circulation. I agree with them, but this lack of circulation and coldness has just recently appeared. Last year or so maybe. Does this sometimes just develop as you get older (I’m in highschool) or can be caused by some kind of vitamin deficiency? If it is nutrition what can I do to help it?