Hollow Stars by Amanda Hocking

Six months ago, Lazlo Durante entered a military quarantine to escape the zombie apocalypse, and he hoped he had somewhere safe to live with his found family.
But when the quarantine falls, Lazlo is alone and on the run through a harsh wilderness. He has nothing but the stars to guide him, and zombies howling at his heels.
As he searches for those he’s lost, he learns disturbing truths about the world he lives in.