George Michael suffered with a secret lung problem for five years.
The Wham! singer – who tragically passed away at his home at the age of 53 from suspected heart failure on Christmas Day (12.25.16) – reportedly never "fully recovered" from pneumonia after he was struck down with the respiratory condition and collapsed while on his ‘Symphonica’ tour in 2011.
A source told the Daily Mirror newspaper: "His lungs never fully recovered. That can happen after a serious bout of pneumonia like George had.
"Sometimes it leaves the lung scarred or damaged, which can lead to a loss of function. Part of the lung basically doesn’t work anymore. It can leave you feeling breathless, as the lungs have a smaller capacity than before."
Doctors raced against the clock to perform a tracheotomy – a small incision in the windpipe – on the ‘Careless Whisper’ hitmaker in order to keep his airways open.
He was unconscious for some time and spent a few weeks in a hospital in Austria – where he collapsed – so that doctors could keep an eye on him.
Speaking about the incident two years ago, George said: "Yes, it almost killed me. On a subconscious level it was very frightening and I’ll probably never feel quite as safe again. But oh my God, I was just so grateful to come out alive and very happy to get back to my home in London."
A full investigation into George’s death is expected to be carried out by the coroner at the beginning of next year but police say they are not treating his sudden passing as "suspicious" – even though it is still "unexplained."
George’s publicist said: "We have been touched beyond words by the incredible outpouring of love for him in the hours and days since his death.
"Contrary to some reports, there were no suspicious circumstances surrounding his death, and from the bottom of our hearts we thank those who, rightly, have chosen to celebrate his life and legacy at this most distressing of times."
A date for his funeral is yet to be announced.