The parents of an 11-year-old girl killed by a rare cancer have spoken movingly of their daughter's final weeks.

Ella Ashberry-Sharp died within three months of being diagnosed with osteosarcoma, a bone cancer that affects about two young people in Leicestershire each year.

Between November and January, Ella changed from being an active, high-spirited girl to being deaf and almost completely paralysed by the cancer, which spread rapidly from her leg to her arm and lungs.

Her parents, Liane Ashberry and Mark Sharp, of Clarendon Park, Leicester, are beginning a campaign of fund-raising in her memory.

Liane, 46, said: "Ella was a fit and healthy girl until she found the lump on her leg. I thought an insect had bitten her."

The next day, they took Ella to the doctor, who sent her to Leicester Royal Infirmary. An X-ray was arranged for two weeks later, but in the intervening days, Ella got weaker. Liane said: "Mark took her to hospital and they gave her an ultrasound and realised it was a bone tumour.

"Two weeks later, she got suddenly worse. One day, she was enjoying school and bouncing on the trampoline in the back garden, and the next day she couldn't walk at all. That weekend she was coughing up blood and we were panicking."

Ella, who leaves sisters Carmel, 15, and Giorgia, 13, went into hospital for chemotherapy, but it became clear to the family she was not going to benefit from further treatment.

Mark, 47, said: "They gave us the option of keeping her at home, and we understood what they were implying. The chemotherapy hadn't done anything and the choice was between more treatment or quality time at home over Christmas.

"When she got home, she stabilised. When the family came, she never wanted to miss out and had a party for her birthday, on December 30. Liane and I couldn't help but think a miracle was happening."

It was not to be. Ella died on January 25 – Carmel's birthday – with Liane and Mark at her bedside. Liane said: " She was fantastic. She didn't complain or say, 'Why is this happening to me?' "

In her memory, the family is raising money for the Bone Cancer Research Trust and the LRI's children's cancer unit. Events include a 100-mile walk around Leicester.

To visit the website go to: www.justgiving.com/ellaashberrysharp