Why are my feet and hands cold all the time?

Okay, so my hands and feet are always cold. but when I put on thick slippers and fingerless mittens they warm up, but when I take them off they go cold really quick. I was at school and it was a cold day, but I felt like I was freezing! I was wearing my uniform with the big school rain jacket, and pants and I was wearing runners, but somehow my feet and hands were SO cold. So I was walking home and I got this pain under the back of my right knee and it hurt so bad. Is it normal or not?