I sometimes feel my limbs go cold and a tightening of the chest , and sometimes when I stand up I get headrush. I am of slim build and around 6 tall, I am 21 years old, too. Often when I notice these symptoms (not all of the time they happen) I feel a tightening in my chest, too. I fear it may be a dietary issue at the least, but I feel some expert knowledge would also help. Thanks -Sylvan