mother, Shannon Pettit, 20, took her daughter Skyla to their GP after she became pale and lethargic, but was told she had the common throat infection and sent away.
Pettit insisted on blood tests and was horrified when doctors revealed days later her daughter had leukaemia, a cancer that attacks bone marrow.
Pettit said: "It was so scary when Skyla was diagnosed. She is so young. I can't even describe what went through my mind."
Skyla is currently undergoing chemotherapy
Skyla's blood cell count was just 34 instead of the average 130 when she was first diagnosed in summer 2015. She is now facing two years of chemotherapy and treatment
Pettit, from Longton, Stoke-on-Trent, said the time between her daughter's diagnosis and the start of her treatment was a whirlwind.
"Two days after going to the doctors she had blood tests at the Royal Stoke University Hospital and then a bone marrow test at Birmingham Children's Hospital," she said.
"For the first six weeks she had to have chemotherapy one day every week at the hospital.
"After her first month of treatment, her legs went weak and she couldn't walk.
"We've been in and out of hospital so much. I just want things to get back to normal. But Skyla is a strong girl.
"Now she has chemotherapy every month, but she also has it in medicine form at home every day.
"Skyla is in and out of school so it's very disruptive to her education. I have to plan everything around Skyla taking her medication."
Kieran said: "It came as a real shock when we found out Skyla had leukaemia.
"She had been ill for a bit, but we just didn't know what was wrong."
Skyla Barker with her grand-aunt Alison Hollran and uncle Kieran Bentley
Kieran's mum, Alison Hollran, 50, said: "I see Skyla everyday. We were devastated when she was diagnosed with leukaemia and still don't know if she's going to pick up.
"She has always been running about, an extremely happy child. But it got to the stage where she didn't move at all.
"She was lethargic and didn't want to get up from the sofa and I instantly knew something was wrong."
Pettit, who also has a one-year-old son, Bentley, added: "Kieran and Skyla have always been incredibly close.
"He understands what she's going through, but Skyla doesn't really, not properly.
"Bentley knows Skyla is poorly but how can you ever properly explain things."
Royal Stoke University Hospital consultant paediatrician Dr Sarah Thompson said: "Skyla has responded well to her initial treatment so we would be quite positive she will have a very good outcome.
"Despite being so young, she has been coping with this incredibly well. She's a gorgeous little girl."
Pettit added: "In two years' time my wish is that she will stop her treatment and be clear, I know she will.
"She will beat this leukaemia, and then, I hope, never have to face it again."