Uncommon symptom every parent needs to know after seemingly healthy little girl, three, was diagnosed with a life-changing medical condition

A three-year-old girl with aggressive cancer 'eating away' at her bone marrow displayed only one symptom before her devastating diagnosis: a painless limp.

Tori Ziebell now wants to raise awareness of the uncommon symptom that was the only sign her daughter Lylah was seriously ill. 

Lylah was a happy and seemingly healthy toddler before doctors revealed on June 27 she was suffering from acute lymphoblastic leukemia (ALL). 

Tori, 27, noticed her daughter had started limping and took her to Frankston Hospital, in south-east Melbourne, where she had X-rays and blood tests. 

The toddler then had an MRI at Monash Children's Hospital, where a doctor discovered a very small abnormality with her bone marrow. 

After more bloodwork results came back, Tori received the news no parent ever wants to hear: her toddler had leukemia. 

'Lylah had no symptoms, just a limp,' Ms Ziebell told Daily Mail Australia. 

'She didn't even complain about being in pain. [Doctors] said she would have been in pain walking with her limp - but we'd asked her every day, because we obviously thought it was painful, [and] she always said no.

'Her bone marrow was being eaten away and that was causing her to limp.'

Lylah has already had two rounds of chemotherapy and while her limp has improved, she is feeling 'a bit nauseous and tired' this week.

For the next nine-and-a-half months, she will have chemotherapy on Fridays and routine tests on Tuesdays until she enters remission.

However, the cheerful toddler hasn't complained once since she was diagnosed.

'She's just a beautiful, happy little girl,' Ms Ziebell said.

Lylah has an older brother, 12, an older sister, nine, and a younger brother.

Tori and her husband Shane, 35, sat the eldest two down to explain Lylah would be staying in hospital for the next nine months.

The couple is taking turns spending time with Lylah in hospital, which is an hour away from their home in Rosebud.

The family is also facing the prospect of having to move house - hopefully to a rental halfway between the children's school and the hospital.

'The house that we're in is old and has asbestos in it,' she explained.

'And it's cold, there's a breeze coming up through the floorboards. We've been looking but we've honestly used up so much money just in this last week.

'We've got to pay for parking at the hospital, the petrol, obviously the other kids, and we've still got to pay rent and bills.'

Tori's sister Amy Ziebell has started a GoFundMe for the family. 

'Shane is self-employed, and with Lylah's recent cancer diagnosis he spends all his time at the hospital with Lylah and currently cannot work at this hard time in life while she is going through chemotherapy, radiation and blood infusions and many surgeries she has already and will endure,' she wrote.

'Any help would be muchly appreciated for this amazing young family and little girl.'