"I think they were struggling to get doctors," Dr Sura on Monday told the coronial inquest into the deaths of six young people who attended festivals between December 2017 and January this year.

When pressed on why he believed that, the Mascot GP said EMS asked him to work at the event, which was attended by 11,000 patrons.

Dr Sura said that he did not feel equipped to deal with the number or type of presentations to the medical tent, which included several drug overdoses, and raised concerns about his lack of experience in the lead-up to the event, including that he wasn't able to manage airways.

His evidence follows a scathing expert report tendered to the inquest about the quality of care provided to revellers Joseph Pham, 23, and Diana Nguyen, 21, on September 15 at Defqon.1, in which EMS was also involved.

As well as the deaths of Mr Tam, Ms Nguyen and Mr Pham, the inquest is also examining those of Alex Ross-King, 19, Callum Brosnan, 19, and Nathan Tran, 18.

Deputy State Coroner Harriet Grahame last week heard Mr Tam consumed a small "rock" of MDMA after drinking about five cups of mixed vodka in 40-degree heat while with his friends at Lost Paradise.

Counsel assisting the coroner, Peggy Dwyer, said that, at 6.25pm, an "unknown female" found Mr Tam lying on the grass in the northern campsite area, conscious, incoherent and in an agitated state.

She said two paramedics attended to Mr Tam and said "this unknown female provided information that she was a friend of the deceased, she was a nurse and the deceased had taken five to six MDMA pills and consumed a litre of vodka".

Dr Dwyer said the woman then left the area and has not been identified by police.

"Police do not consider the information she provided to be reliable," she said.

Mr Tam's mother, Julie, took to Facebook on Friday to say "we have not yet been contacted by the young lady who was with him during his last moments before becoming unwell and being found."

"As Joshi’s mum I ask you to please come forward and provide the details to the missing gap in time between when Josh was last seen by his mates to when he was found by the medical staff," Mrs Tam said.

"What occurred during this time to me as his mum would provide much comfort in establishing how long perhaps he was unwell. We understand her to have identified herself as a nurse and a friend or acquaintance of Josh.

"If you are this girl or know who she is please private message me. I would like to thank you for being with him at this time and allow me to know what transpired in his final moments. This would give me some peace in a time in my life when I have little."

She said she wanted to reassure the woman the purpose of the inquest was to establish the chain of events for each of those who died "so things can be improved going forward".

Detective Senior Constable Rodney D'Bras told the inquest police had tried to find the woman on social media, as well as issuing a media release after Mr Tam's death.

He said investigators were not pursuing her "from a policing side of things" but wanted to verify the information she reportedly provided that day. The inquest has heard the woman was of "Asian" background.

The inquest heard Mr Tam's friends became concerned when they hadn’t seen him for some time and they went in search of him. When one of them called Mr Tam's phone, it was answered by police.

Mr Tam was taken Gosford Hospital by ambulance, arriving at 7.05pm. He was pronounced dead at 7.52pm, with an autopsy later finding he had died from complications of MDMA use.

A childhood friend of Mr Tam, who accompanied him to the festival, told the court Mr Tam told him he had managed to obtain three grams of MDMA in crystal form, which was distributed into three zip-lock bags.

He said temperatures were extremely high that day and, at one point, he and Mr Tam had put their heads under a shower, which he described as "boiling hot".

Asked what lifesaving measures should be implemented, the friend said it was "stupid not to have pill testing".

"If we can save one life then we've done our job," he said.

The friend, whose identity has been suppressed, urged others not to touch MDMA after telling the inquest that he previously ignored the dangers of the drug.

"I didn't think anyone would die," he said.