remedies for acne on back?

I've had acne on my face since my early teens, which has gradually
improved considerably over the last 2 years (I'm 21 now), so it is no longer
a big problem. Around age 15, I developed very mild acne on my upper back
for a few months, and then it disappeared until about age 18, when it came
back much more severe (bigger and more sore) and more widespread (all the
way down my back, and occasionally on my chest). This pretty much coincided
with growth of chest hair and even some stray back hairs in the last couple
years. Maybe a hormone thing? Right now, it's worse than it's ever been.
It is also scarring, so even during rare times where I don't have any
new acne, my back still looks terrible. Are there any foods I should avoid
to prevent breakouts in this area? The only food that seems to make my
breakouts worse is chocolate, which I'm staying away from. My face didn't
seem to respond, good or bad, to anything I tried. It just ran its course
and sort of fizzled out. Can I expect the same for my back, and when can I
hope for it to improve? I find it strange that as my face improved, my back
has worsened.
Thanks for any input
Dan