Connor Pleasance, 26, from Brampton, was otherwise a healthy man before he started to feel ill in June and attended Barnsley Hospital.
The dad of five-year-old Grace and two-month-old Beau found out his gall bladder had ruptured whilst in A and E, prompting a further stay in hospital.
His mum, Jo Pleasance, told the Chronicle: “He also had pneumonia so he had to stay in hospital for two weeks.
“He seemed to be getting a bit better and he was allowed to come home for three weeks.
“He started to feel poorly again and he had an hospital appointment where he found out he had severe pneumonia and had to stay in the Intensive Care Unit (ICU) at Barnsley Hospital.
“Connor was on oxygen all the time and he started to get better day-by-day.”
However, last Monday everything seemed to deteriorate as he was placed into an induced coma as he became critically ill with lung fibrosis.
Doctors told his family they think some bacteria from his ruptured gall bladder is attacking his lungs.
“He took a turn for the worse and had to be put into an induced coma,” the 48-year-old said.
“He’s currently on life support but there’s no change in him as of yet.
“”He’s still fighting and I’m with him in Leicester as he was blue-lighted down here to Glenfield Hospital on ECMO care.
“I’m not planning on leaving until he’s coming home with me.”
Extracorporeal membrane oxygenation (ECMO) is a life support machine.
People who need ECMO have a severe and life-threatening illness that stops their heart or lungs from working properly.
Jo said she doesn’t understand how someone so healthy can deteriorate so quickly.
“It’s just so emotionally draining,” she added.
“I can’t believe someone so young, who’s usually so fit and healthy, could get his poorly so quickly.
“It’s just so hard to believe.
“I’m not going to leave him until he’s home with me.”
To help support Connor and his young family with girlfriend Jade, a fundraiser was set up by a friend which has raised more than £4,000.
They’re anxiously waiting at home for any news from Jo, whilst Grace is drawing pictures of her dad to put around their family bed whilst he is gone.
“Connor is a gamer so there’s been donations coming in from all over - it just shows how popular he is,” Jo added.
“It’s so overwhelming how much money has been raised to support the family.
“I won’t be able to work and neither will Connor so it’s really helpful.”