When Georgina Bloomberg stepped off the back of her second ride of the day on a summer afternoon, she felt a familiar pain as soon as her feet met the ground. It crept its way through her back and shot down her leg. She wasn’t worried. The pain was recognizable. She felt it every day. Later that evening, she braced herself against the bathroom sink while she brushed her teeth through the piercing pain. The next morning, she couldn’t manage to walk at all.