Talented dancer Darcie Mathison, from Rotherham, was first taken to hospital two weeks ago when she choked on a carrot while eating a meal.
Her mother Sam Day, 34, noticed the following day that she was struggling with her balance.
Darcie was taken to Rotherham General Hospital for a second time on the Tuesday, when Sam returned from her shift as a nurse to find half of her daughter's face had gone limp.
But Sam, along with Darcie's father Tom Mathison, 33, her brother Cameron, 12, and 11-year-old half-sister Gracie were given the devastating news that a mass had shown up on an MRI scan of the youngster's brain.
By the Wednesday, she had been transferred to Sheffield Children's Hospital where specialists diagnosed her with a Diffuse Intrinsic Pontine Glioma (DIPG) - the rarest form of brain cancer in children - which is incurable.
Darcie's uncle Joe Mathison said the diagnosis showed how "24 hours can shatter the lives of one family".
Mr Mathison, 29, from Leeds, is now raising £10,000 to fund a specialist chair for his niece, as well as funds to help his brother and Ms Day who have had to put their jobs on hold.
The youngster is still in hospital after undergoing a round of chemotherapy, and may start radiotherapy next week if doctors decide she is well enough.
"As soon as they found she had a tumour she was transferred to Sheffield Children's Hospital," said Joe.
"That's when they confirmed she had DIPG.
"At first, we thought the worst it could be was Bell's palsy (facial paralysis)."
DIPG is an extremely rare form of tumour that occurs in the pons - the centre of the brain stem - in developing brains.
"We've been told it's a very aggressive form," Joe added.
"Less than ten per cent of children survive for two years. The worst case scenario would be around six to nine months for Darcie.
"I don't think she really knows or understands. She's such an active little girl who's always running around and can't sit still. Just two weeks ago she was doing backflips on the trampoline.
"She has been dancing since she could walk and she's obsessed with unicorns - I think she must have around 100 of them in her bedroom."
Mr Mathison is now planning on doing the Yorkshire Three Peaks challenge with his partner, Jake, as well as a half marathon in order to raise as much money as they can for the family.
A charity boxing match has also been organised, while Darcie's friends from her dance group, Rotherham Dance Centre, have also organised a fundraising event.
Darcie's family are also being supported by Clic Sargent, which is the UK's leading childhood cancer charity.
Mr Mathison added: "Tom and Sam have just gone into full parent mode and are staying in a home next to the hospital so they can be with her.
"Darcie is on a drip and being fed through a tube, but she is still smiling."
You can donate to the GoFundMe page to help the family here.