The 'Glad You Came' hitmaker went under the knife on the day he turned 20 to repair a haemorrhaging vocal cord, and he says he had a mini-meltdown in front of surgeons just moments before the operation, reported E! online.
"It has been a scary time, I think just before I went under the anaesthetic for the operation I kind of had a bit of a panic attack. I was like, 'My career is in your hands'," he said.
"The fans have been incredible. They really kept me going.
They were always online (on Twitter) going, 'How you doing? How you doing (sic)?' but I didn't want to say too much because they were always like, 'When you back (sic)?'. That was always the first question and I didn't want to say specific dates just in case I didn't make it.
"I had to see the doctor before my first performance and if he said no I didn't want to let anyone down," he said.