A former police officer paralyzed from the neck down is helping other spinal cord injury patients recover, even as he continues his own recovery. John Tellis, of Mount Pleasant, was paralyzed last August after a freak accident while walking his dog. "I don't know if his leash got wrapped around my feet or if I just slipped, but I wound up falling straight back and heard a loud snap," Tellis said. "It was probably the worst and scariest moment of…