TEMPE, Ariz. — A couple of months ago, Cooper Hernandez was just like any other 10-month-old. 

He was smiling, laughing and had just learned to crawl, but that changed in a matter of just four short hours in September. 

Cooper's mom, Lexi Hernandez, left him with his baby sitter. She called to tell Lexi that Cooper had been fussy before his nap, but when he woke up, something was wrong. 

It seemed as if Cooper wasn't able to lift his head. 

"He just was floppy, wouldn't move," said Lexi. "He still moved his legs, but not his arms, so it was his arms and neck that were mostly affected."

Lexi and her husband took Cooper to the Emergency Room, where things went from bad to worse. 

Eventually, doctors put in a breathing tube because Cooper couldn't breathe on his own. 

"It was really stressful. I mean, you just want to get the name of what it is and fix it," Lexi said.

The name was Acute Flaccid Myelitis, or AFM, a mysterious polio-like illness that has been popping up across the country. 

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Doctors don't know much about it, including what causes it, but the CDC had 201 reports in forty states in 2018. 

Four of those cases were in Arizona. 

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Doctors tell Lexi, Cooper may be able to walk one day if put in the right intensive rehabilitation program. 

They've recommended the Kennedy Krieger Institute in Baltimore, which specializes in AFM rehab, but at first, Lexi's insurance turned down the claim. 

After an appeal, Cooper got approved. He will now begin a long journey toward recovery. 

The CDC is currently investigating AFM cases and has information on how to spot symptoms in your child.