By Ken MacLeod

LEE (CBS) – A little boy is recovering at his home in Lee, Massachusetts from a frightening COVID-19 surprise his parents never expected. Four-year-old Joseph Arriola is turning the corner now thanks to convalescent plasma.

“And he has to get the antibodies for him to get better,” Joseph’s mother, Fatima Arriola, told WBZ-TV.

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Trouble began when the whole family got COVID back in December, something Fatima believes she brought home from her job as a medical assistant at a Boston hospital.

“Yes,” she said, “I feel guilty.

Joseph Arriola (WBZ-TV)

But the worst came weeks later, when her son, who’d never shown any COVID symptoms, got very sick with a fever, vomiting, headaches, and painful swelling everywhere.

“They said just give him some Tylenol and some ibuprofen and he’ll get better,” Fatima said. But he didn’t.

What followed was a string of visits to Massachusetts General Hospital, where doctors diagnosed Joseph as one of the rare, poorly understood cases in which COVID-19 had morphed into Multisystem Inflammatory Syndrome.

It’s a dangerous inflammation of the body’s organs, and in Joseph’s case, it’s his heart.

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“I thought everything was okay and then this happened,” says his mother. “He was screaming in pain.”

Now, Joseph is getting better, but his mom and dad both missed weeks of work to care for their son and the first medical bill came in at $67,000.

“And I’m so scared by that,” said Fatima, “because my insurance only pays 80%.”

So, her friends at work started a GoFundMe page to help. And Fatima, a U.S. citizen born in El Salvador, is working 12 hours shifts hoping to make the extra money.

That’s quite on strain on the family considering she commutes to Boston every day from Lee on the opposite end of the state, and is also taking classes at Roxbury Community College to become a registered nurse.

For now, though she’s more concerned about warning parents who think their young children won’t suffer any serious ill-effects from Covid.

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“But that’s not true,” she says, “because this could happen to them. We must try to be alert for the kids.”

Ken MacLeod