Four-year-old Lewis Jeynes is trapped in a body that doesn’t work: He can’t walk or talk, move his limbs or support his own head, London’s Daily Mail reported Wednesday.

Yet two years ago, the blond-haired, blue-eyed little boy was an active toddler, filled with energy.

And to make matters worse, doctors have no idea what’s wrong with Lewis.

Blood tests, biopsies, MRIs, allergy tests and even a spinal tap have not given his family a definitive diagnosis.

“On paper, Lewis is perfectly healthy,” Lewis’ mom, Samantha, 39, who lives in Doncaster, England told the Daily Mail. “No one can explain why this has happened to him.”

For the first two years of his life, Lewis was healthy. Just before his second birthday, he started limping. An X-ray showed inflamed tissue around his hip, which doctors said was normal for boys his age.

Instead of getting better, however, Lewis got worse. In July 2006, he had a seizure and an MRI scan showed slight abnormalities in his brain, although doctors couldn’t come up with a conclusive diagnosis.

Within months, Lewis lost neck and arm movement, and lost the ability to swallow food.

Now, he is fed through a tube and sits in a wheelchair. Though his condition has stabilized, his mother is in a constant state of worry.

“When Lewis was a baby, he was so perfect, I never ever thought something so terrible as this could happen to him,” Samantha Jeynes said.

Click here to read the full story from the Daily Mail to and see pictures of Lewis.