Malachi Castner, 23, said he didn’t always sleep on the Blue Line train to avoid the cold and rain. He didn’t always start his day early by shooting up. He was once a teenager on his high school’s wrestling team.

       But it was after he tweaked his back while wrestling an opponent as a junior in high school and a doctor prescribed him OxyContin that he descended into addictive patterns that stuck.

       He sat inside West Suburban Medical Center last Tuesday morning, scarfing down a sandwich and using shaking hands to open cartons of apple juice. He said he felt chills, his nose was running and his body ached. Over the next few hours, he was just anticipating worse withdrawal.