Ariana Grande was gripped by "wild dizzy spells" and struggled to breathe for months after the Manchester terrorist attack.
The 'No Tears Left to Cry' hitmaker has suffered from anxiety in the past but never felt it physically until after the bombing at her concert in the English city last May.
She said: "When I got home from tour, I had really wild dizzy spells, this feeling like I couldn't breathe. I would be in a good mood, fine and happy, and they would hit me out of nowhere. I've always had anxiety, but it had never been physical before. There were a couple of months straight where I felt so upside down."
In the wake of the tragedy, Ariana flew back to America but returned just a few weeks later for the One Love Manchester benefit concert to raise money for the victims and their families.
And the 25-year-old star had vowed not to perform anywhere else but the city before resuming her 'Dangerous Woman' tour.
Her mother Joan recalled to America's ELLE magazine: " "It was two or three in the morning; she crawled into bed and said, 'Mom, let's be honest, I'm never not going to sing again. But I'm not going to sing again until I sing in Manchester first.' "
Ariana said: "Why would I second-guess getting on a f***ing stage and being there for them? That city, and their response? That changed my life."
The 'Side to Side' singer admitted the incident has completely altered her outlook on life.
She said: "You hear about these things. You see it on the news, you tweet the hashtag.
"It's happened before, and it'll happen again. It makes you sad, you think about it for a little, and then people move on. But experiencing something like that firsthand, you think of everything differently."