What Causes Numbness In The Arm?

I have been told I have the flu!my left arm has gone numb from the shoulder down I can move my arm and hand but it feels strange almost like it doesn't belong to me! I've tried warming it clenching my hand into a fist this has not helped my fingers are now White my hand is freezing even though I've had it warmed and it's still cold when pressing the ends of my fingers there is very little colour to them this happened all of a sudden I can still grip with this hand but it feels very strange!! Help