Zoey and Sassafras: Gnomes and Sneezes: Book 10 by Asia Citro

When Sophie shows Zoey a special hidden room in her new house, Zoey thinks things can't get any more exciting. But then Zoey hears something Sophie can't. . . could it mean a new magical creature? Soon Zoey learns about a mysterious illness, but she just can't seem to cure it. Will Zoey and Sassafras be able to help their new friends in time?