Two-year-old Brooklyn Harrold died from blood poisoning just hours after doctors told her mother she was being 'paranoid' about her daughter's health.
Brooklyn was taken to Northampton General Hospital on May 9, after her mum Leanne, 20, became concerned about the fever and high temperature she was suffering from.
Her mum claims she begged for Brooklyn to have anXx-ray or be transferred to Birmingham Children's Hospital, but instead, she says, they were kept waiting for five hours before eventually being admitted in to the hospital over night.
Brooklyn was discharged at 9pm the next day, allegedly without having undergone any blood tests.
Leanne and Brooklyn went to her grandparents' house the following day, where an ambulance was called to take her back to hospital after she turned yellow.
Full blood tests were then carried out on her, and the decision was made to transfer her to Birmingham Children's Hospital.
Doctors allegedly told Leanne they had to put Brooklyn in a medically induced coma in order to insert a ventilation tube into her. The little girl then died from septicaemia just minutes after being sedated.
Ms Harrold said that medical staff originally told her they suspected Brooklyn had gastroenteritis. She says she was called a 'paranoid mother' when she asked for her little girl to be re-examined.
The toddler had been born with with a rare heart disease, truncus arteriosus, which caused her heart to have one large artery instead of two smaller ones. She had a history of medical problems and had undergone surgery to fit a tube which connected her heart to her lungs.
Ms Harrold, from Northampton, says she is now taking legal action against the hospital . She said the treatment Brooklyn received was 'unacceptable'.
"I got her up on the Saturday morning and she was yellow. She was as yellow as a banana skin - I was freaking out," she said. "I got a taxi to my mum's, and she took one look at Brooklyn and rang an ambulance. Her whole body was swollen and you couldn't pick her up because she would scream."
Leanne says that the hospital discharged Brooklyn despite the fact her temperature was 'sky high'.
When the decision was made to transfer her to Birmingham Children's Hospital, Leanne was in agreement
"I said that's fine, I wanted this done two days ago on Thursday," she said. "They said they needed to put her in a coma and put her on life support to get her there. She died for three minutes when they were trying to get the tube into her and they massaged her heart to get her back.But she died after they had done it and they couldn't save her."
Brooklyn's great-grandfather, Michael Diggin, said he thinks the little girl was treated differently by staff because of her heart condition, and that if doctors had acted more quickly, she would still be alive.
"It was probably 50/50 that she may die of septicaemia, but if you catch it earlier you enhance the chances of survival," he said. "I believe they lost a 36-hour window to treat her with antibiotics."
Ms Harrold says that Brooklyn's sister, Tia, four, keeps asking when she is going to see her sister again.
"I have taken her to Brooklyn's grave, but I can't explain what has happened to a four-year-old," she said.
A spokesperson for Northampton General Hospital said they are carrying out an investigation into the circumstances surrounding Brooklyn's death.