i rarely have any acne ever since on my teen years nothing has changed even if i'm here in the UK now in fact my skin is way better than before. i am NOT saying i have perfect skin though: nono-1-1: I have a uneven skintone and oily T-zone
Maybe the reason why you got acne at the back is due to stress i'm no expert but you might be interested to read this http://acne.about.com/od/acnebasics/...acnebasics.htm