When she moved to Barrington, Rhode Island, Andrea Caesar was an active, happy, vivacious ten-year-old who loved to play kickball and hang from the monkey bars. A year later, Andrea had trouble catching her breath while running, was plagued by migraines, and battled constant muscle aches. Andrea had changed as a person; she was the kid who was always missing school. Although she did not know it at the time, she had contracted Borrelia burgdorferi, better known as Lyme disease.

Caesar, who was finally diagnosed at age thirty-six, shares a raw and honest look inside the mind of a...