She was set to host the 2016 ARIA Awards last week but pulled out after falling ill.
Now, those close to Delta Goodrem have serious concerns for her heath, according to Woman's Day.
'Everyone's really worried about Delta,' a source told the magazine. 'To pull out at the last minute means there must be something seriously wrong with her.'
According to the magazine, concerns were raised over her health earlier this year during the filming of her music video for The River.
In the video, the songstress takes part in what looks like an emotional baptism ceremony in 'The River'.
'Delta couldn't move a muscle without someone fussing over how she was feeling,' the source reportedly said.
'Her manager almost killed the whole shoot because he was worried about how long she was spending in the water.'
Delta's health was first thrust into the spotlight in 2003.
Aged just 18, she was diagnosed with a rare type of cancer called Hodgkin's Lymphoma, just months after the release of her debut album Innocent Eyes.
She underwent chemotherapy to treat the disease and announced she was in remission in December that year.
Less than a year later she released her second studio album Mistaken Identity, which went on to be certified five times platinum after selling more than 350,000 copies.
Delta's new album Wings of The Wild flew to the top of the ARIA charts when it was released in July, but has since slipped to No. 42.
Daily Mail Australia has approached Delta's representatives for comment.