The 23-year-old Brit has had to pull the plug a 10-city concert series, which was due to kick off in Atlantic City, New Jersey on October 7, after being ordered to rest her voice or risk losing it for good.
'Singing is literally my life, it's my hobby, my love, my freedom and now my job,' she wrote on her official website Tuesday. 'I have absolutely no choice but to recuperate properly and fully, or I risk damaging my voice forever.
'I will be back and I'm gonna smash the ball out the park once I'm touring again. I apologise from the bottom of my heart, sincerely I do.
'I know it's not only disappointing because of the show, but it's plane tickets, hotel bookings, birthdays, anniversaries and time wasted.
'But please have faith in me that this is the only thing I can do to make sure I can always sing and always make music for you to the best of my ability.'
The singer cancelled a US tour in June after being diagnosed with laryngitis. She suffered a respiratory and chest infection just months later. She will now undergo 'vocal rehab' to improve her 'overall stamina'.