Madonna was reportedly holed up in the recording studio with Katy Perry just hours before she was found unresponsive in her New York home.
The singer, 64, was rushed to the ICU and intubated after being found slumped on the floor of her New York City apartment on Saturday, prompting family to rush by her side and prepare ‘for the worst’.
It is claimed she looked thin and exhausted in the days before she nearly died from a serious bacterial infection.
But the Like A Prayer hitmaker is said to have been working in the studio with fellow recording artist Katy, 38, just hours before she fell ill.
A source told The Sun: ‘Madonna has long admired Katy and they have worked together before but never managed to actually put anything out.
‘Madonna has been working around the clock to make sure both her music and her world tour are second to none.
‘Obviously everything has been put on hold now but the fact she was in the studio with Katy just hours before being rushed to the ICU shows how determined she was to push ahead despite feeling unwell.’
MailOnline has contacted representatives for Madonna and Katy for comment.
The pop legend is now said to be back home and recovering, although it could take months before she is back at full strength.
It is still not clear what type of infection she had, but experts said that intense preparation for her tour and gruelling workouts may have left her more susceptible to normally harmless infections.
After reviewing photos taken in the days before her illness, doctors said she looked ‘exhausted’ and appeared ‘thin’.
In a photo posted to Instagram four days before her hospitalisation with the caption ‘the calm before the storm’, she is shown lying on the floor while wearing a black jumpsuit and fishnet tights.
Her hair and makeup are immaculate with nothing out of place, although she also appears ‘thin’ — said Dr Thomas Moore, an infectious diseases expert at the University of Kansas.
Dr Fischer, who is also a former emergency care doctor in New York City, told DailyMail.com after viewing the photos that she was clearly ‘exhausted’.
‘She looks exhausted,’ he said.
‘Intense rehearsing and the stress associated with large-scale performances are undoubtedly risks for immunosuppression and unwanted health issues.
‘It’s the responsibility of the physician to point this out. Just because someone is an international celebrity doesn’t mean they’re invulnerable.’
Dr Thomas Moore, an infectious diseases expert at the University of Kansas, said about the images: ‘She doesn’t look much like the Madonna I am used to seeing.’
He told DailyMail.com: ‘She looks thin from the photos. She does not look well but it is all relevant.
‘She is such a dedicated performer that I wonder if she was not feeling well but then pushed herself too far.’
It has not been revealed what serious bacterial infection Madonna suffered, although rumors suggest it could be sepsis — a life-threatening reaction to an infection that sees the immune system attack the body.
Bacteria can enter through cuts, wounds and the digestive system, among other areas. Sepsis is triggered when the bacteria gets into the bloodstream.
Dr Fischer, who believes sepsis is the most likely explanation, said that the star should not have been discharged from the hospital so early.
The doctor, who has treated many celebrities, Oscar nominees and TV stars during his more than 40-year career, said doctors should have held their ground.
‘This discharge might put her life in jeopardy,’ he said.
‘No matter how hard [celebrities] push you, you don’t discharge them so quickly.
‘They may be a celebrity on the outside, but on the inside, everyone is the same and has the same organs.’
