Polly Everett's Other Worlds by Jo Mabey

Aaaaaaaahhhhh......... chooooo!

Strange things are happening to thirteen-year-old Polly Everett. Unsettling changes
to her world lead her to question her memory – and her sanity – but no-one believes
her.

With the help of Mr Jenkins, her science teacher, Polly realises she’s not going mad
– she’s travelling between parallel universes. And these dimension-hops seem to be
triggered whenever she sneezes!

Polly finds herself propelled from universe to universe, where familiar people are
disturbingly different, in a thought-provoking adventure that provides a unique take
on the ‘what ifs’ of everyday life.