Be Not Far From Me by Mindy McGinnis

Ashley knows this truth deep in her bones, more at home with trees overhead than a roof. So when she goes hiking in the Smokies with her friends for a night of partying, the falling dark and creaking trees are second nature to her. But people are not tame either. And when Ashley catches her boyfriend with another girl, drunken rage sends her running into the night, stopped only by a nasty fall into a ravine. Morning brings the realization that she’s alone – and far off-trail. Lost in undisturbed forest and with nothing but the clothes on her back, Ashley must figure out how to survive despite the red streak of infection creeping up her leg.