A boy in the UK has died from brain cancer after his tumour was missed by doctors who diagnosed him with acute constipation.

Logan Allebon, four, fell ill in 2018, complaining of headaches.

Concerned parents Nik and Helen Allebon took their son to the local GP who diagnosed constipation, attributing other symptoms such as loss of appetite and a slight wobble when Logan walked to the same condition.

The boy's devastated parents are now speaking out about their tragic loss, to raise awareness of the symptoms of brain cancer.

Logan Allebon died from brain cancer. (Facebook)

When his son failed to recover from his illness, his father Nik Googled his son's symptoms.

"It suggested a brain tumour, but then again, that's Google for you - you type in your symptoms and it nearly always comes back with cancer," said Nik told The Mirror.

Logan eventually became listless and disengaged from his favourite activities.

"He couldn't even stand up on a chair and hold on to the side without ending up in tears," Nik continued.

Logan was rushed to hospital and diagnosed with Medulloblastoma, a cancerous tumour that affects the cerebellum and can spread to the rest of the brain and the spinal cord.

Logan was scheduled to undergo surgery three days later, smiling at his parents and saying "Mummy" and "Daddy", but following the surgery to remove the tumour in August, 2018, he never spoke again.

"It was in the void where the tumour had been and it was all around the brain," Nik says. "It was all the way down his spinal cord and there was so much of it, some had dropped off the bottom and was just floating around at the base of his spine."

Further treatment was suggested however the couple decided to take their son home to die due to the extent at which the cancer had spread.

The little boy fell ill and had trouble walking before his diagnosis. (Facebook)

Logan came home on September 26 and died on October 14, just nine weeks after the original diagnosis of acute constipation.

Nik warns parents to be on the look out for symptoms of brain cancer in their children, including persistent headaches, balance problems and a change in behaviour.

They have set up a Facebook page called Love From Logan, urging people to perform acts of kindness in their son's name.

"We want people to know about Logan - it's a way of keeping him in our life," Helen said.