George Michael was reportedly found unconscious at home a few months ago.
The 'Faith' hitmaker has left friends worried after he collapsed at his north London mansion last Thursday, as it has now emerged it was the second time recently that emergency services have had to attend to him.
A source told The Sun newspaper: "George's latest collapse is the second time this year that emergency services have attended his home.
George - who announced earlier this year he had quit smoking cannabis - is said to have become increasingly reclusive in recent weeks and has been spending most of his time at home.
One worried friend said: "There is a real concern that George does not drift down a dark path again."
A spokesperson for the 50-year-old star said he is now "well and resting" following his mystery illness last week.
George almost died of pneumonia in 2011 and has had to deal with a number of health problems over the years, including depression and drug addiction, which has seen him arrested multiple times and he served an eight week prison term in 2010.
Last year, he was also airlifted to hospital after he fell out of a car on the M1 and was treated for "superficial cuts and bruises".