No parent ever wants to see their child sick, so you can imagine what Antonia and Andy Watson must have felt when they found out that their son was seriously ill with a rare disease.

When 5-year-old Mckenzie Watson's face and midsection started to appear bigger, his parents simply chalked it up to weight gain.

"The first time it happened, we just thought he had put on weight over Christmas," Antonia, 26, recalled.

It wasn't until 11 days later, when he had to be rushed to the hospital, that they realized what was really wrong with their son. After running a series of tests, doctors found that Mckenzie's lungs were leaking fluid into his abdomen.

The liquid build up caused his belly to swell up so much that it looked like he was "nine months pregnant and about to pop," according to his mom.

"It was so scary because his skin was so tight ... as though it were a fully formed bump," she added.

As it turned out, Mckenzie was dealing with a form of kidney disease that affects 2 in every 10,000 children in America.

Doctors diagnosed little Mckenzie with nephortic syndrome, a condition which occurs when the small blood vessels in the kidneys that filter waste and excess water from the blood are damaged, according to the Mayo Clinic.

The lack of filtering causes the body to excrete too much protein, which leads to swelling in different parts of the body, including the feet, ankles, legs, and in Mckenzie's case, the face and stomach.

There is no known cure for the condition, but the symptoms can be managed with blood thinners, water pills, and immune-system suppressing treatments like chemotherapy.

Mckenzie's case was severe and required him to undergo eight weeks of chemotherapy to treat.

He also had to take other medications to help his kidneys function better.

"We have to give him steroids every day to stop his kidneys from leaking protein," Antonia 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."

Since starting his treatment plan, Mckenzie has shown significant improvement and was even cleared to go home.

However, his parents have to closely monitor is diet or else he could relapse.

"He's not allowed any salty food and he's only allowed a pint and a half of water each day," explained his mom. "He's relapsed six times, but three of those times we managed to keep it under control at home. Each one was terrifying," she added.

The family now knows how to deal with Mckenzie's needs, so they're doing their best to make sure he doesn't end up in the hospital again. The good news is that when nephrotic syndrome is managed properly, the symptoms could disappear once the child reaches puberty.

The Watsons have since started a GoFundMe page to raise money to help find a cure for the rare disease. They've already raised half of their goal amount.

We're wishing Mckenzie a speedy recovery.