A mum says she is watching her four-year-old son fight for his life after his tummy ache turned out to be a rare kidney disease.

Leslie Cooke was diagnosed with Wilms tumour after he woke up to find a tennis-ball-sized lump on his stomach.

His cancer is categorised as Stage 4, the most advanced phase, with the disease spreading to his lungs, liver, main artery and backbone.

His mum Jessica said: “He's amazing. He's strong, he's a fighter and he's a hero.

“I mean it when I say I've watched him fight for his life.”

The 32-year-old from Milton Regis, near Sittingbourne, also has two daughters, Alisha and Josie. She is a full-time carer for Alisha, who is blind, autistic and has microcephaly – a condition where the head and brain develop abnormally.

“You don't really know how to feel,” she explained. “You just feel numb.

“When I know I have to go to hospital, as soon as I get there I can't breathe until I get back out.

“I have to go into that mum zone and block out everything.

“I do what needs to be done and then I can breathe when I'm home – that’s the only way I can describe it.”

The mum-of-three suspected something was wrong with her son last December.

She took him to Faversham Urgent Treatment Centre and was referred to Medway Maritime Hospital, but was told it was just a tummy ache.

“He was quite tired and kept getting belly pains,” the mum explained. “He was holding himself so tight where he was in so much agony.

“In January, he was sleeping 20 hours a day and when he was awake he had no energy.

“He stopped eating and kept getting higher temperatures as well.”

Jessica claims she was taking him to hospital every two weeks and that doctors put the cause down to an unidentified infection.

After asking for different blood tests to be done, it was discovered that Leslie was also anaemic.

At the end of March, a lump suddenly appeared on the left side of the four-year-old’s stomach.

Jessica added: “He woke up and it was there. It was quite big and poking out on the side.

“It was about as large as a tennis ball – turns out it was his kidney.”

Leslie was diagnosed with Wilms tumour, also known as nephroblastoma.

Around 85 children between the ages of 0 and 14 are diagnosed with the rare kidney cancer every year in the UK.

“It was bittersweet,” Jessica said. “I'm glad that the lump came up because I still might be sitting here wondering what's going on.

“I felt like I was going out of my mind to be honest. Everyone was just looking at me like I was making it up.

“It does make me angry, because if I was listened to at the beginning then it might not have got that serious.”

Interim Chief Nursing Officer for Medway NH Foundation Trust, Sarah Vaux, said: “We understand a cancer diagnosis is distressing and our thoughts are with Leslie and his family during this difficult time.

“We are committed to providing the very best of care to our patients and we would encourage Ms Cooke to contact us so we can investigate her concerns.”

Leslie has spent three months at The Royal Marsden Hospital in London.

He has since been allowed to go home but has to make regular trips for his chemotherapy treatment.

Following that, Leslie is set to have three weeks of radiotherapy. The four-year-old also has to have injections every day, which help reduce blood clots.

Jessica said: “I think he knows he is poorly because when we were in hospital he didn't even ask to come home.

“He knew he was there for a reason, but I just don't think he understands what it is.

“The other day he took his first steps. He's lost mobility as well, so he is learning to get back to a little bit of normal.”

Friend Alison Godden has been helping the family out over the last few months.

She has set up a GoFundMe page with the aim of raising £2,000 for Cancer Support UK in Leslie’s name.

She is also organising a charity skydive, with friends Joe Bone and Elijah Mealing set to jump out of a plane at Headcorn Aerodrome at 1pm on Friday, August 30.

If you would like to donate please click here.

Alison, 55, said: “With what Jessica’s going through, she's coping really well.

“She's got a lot to deal with and it sort of hit her from nowhere.”