When a child gets sick, it can be a piece of cake: give them enough love and care, and they’ll bounce back within a few days. But when the sickness turns out to be more serious than you thought, it’s every parent’s nightmare.

When 5-year-old Mckenzie Watson’s face and belly started to get fuller, his parents assumed he was packing on a few pounds (sweets will do that). But then it got worse, and 11 days after being rushed to the hospital, they found out what was really going on: Mckenzie’s lungs were leaking, filling his abdomen with fluid. He was diagnosed with a kidney disorder called nephrotic syndrome.

Mckenzie’s mother, Antonia Watson from Doncaster, England, told Daily Mail that at his worst, her son looked “as though he was nine months pregnant and about to pop.”

“It was so scary because his skin was so tight … as though it were a fully formed bump,” she continued.

According to Mayo Clinic, nephrotic syndrome is usually caused by damage to small blood vessels in the kidneys that filter waste and excess water from your blood. As a result, too much protein is excreted and swelling occurs (along with Mckenzie’s inflammation in his face and stomach, it’s common that such swelling can occur in the feet, ankles and legs).

American Kidney Fund states that, in children, nephrotic syndrome effects around 2 in every 10,000 and is most common among 2- to 6-year-olds. With blood thinners, other medications or chemotherapy, the disorder’s symptoms are treatable, but there is no known cure.

Watson, 26, said that worst of all, it causes Mckenzie excruciating pain. He is now on an eight-week chemotherapy plan, which will weaken his immune system in order to treat him.

“We have to give him steroids every day to stop his kidneys from leaking protein,” Watson said. “And now he’s having to have a daily dose of chemotherapy to hopefully kill off his immune system to stop it attacking his kidneys.”

Mckenzie is back home but needs to be monitored closely. He can’t eat salty food and is only allowed a pint and a half of water each day. If his disorder isn’t controlled, he can relapse. This has unfortunately occurred six times, three of which landed him in the hospital.

“We know when he’s about to relapse too — if he doesn’t go to the toilet for a long time, that’s how we know,” Watson said. “He starts swelling up because his body retains the water.”

While relapses are common, it’s reported that, with the right treatment plan, nephrotic syndrome can be maintained and symptoms typically fade once children reach puberty.

The family is raising money on GoFundMe to find a cure. In only one month, they’ve reached their goal of $2,600, and Mckenzie’s uncle has started his own page to support the cause.

The boy’s father, Andy Watson, wrote on Facebook yesterday that the doctors are happy with Mckenzie’s progress. His urine has tested negative for secreted protein for three days straight!

Here’s hoping this cutie finds his smile back. It’s a good one.