Mary Lou Retton's daughter says Olympic-winning mother faced recent 'scary setback' in pneumonia fight

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Mary Lou Retton, who captured the attention of the nation when she won the all-around women's gymnastics competition at the 1984 Summer Olympics, had a "scary setback" as she fights a "very rare form" of pneumonia.

In the first update in four days, Shayla Kelley Schrepfer, Retton's daughter, that things seemed like they were headed "on the up and up," but things took a turn for the worse on Tuesday.

"Basically at the beginning of this week, we were going on the up and up," Schrepfer said in the Instagram post. "We were so excited seeing so much progress. And then yesterday, we had a pretty scary setback."

(L-R) Ecaterina Szabo, Mary Lou Retton, Simona Pauca, Women's gymnastics medal ceremony, Pauley Pavilion, at the 1984 Summer Olympics, August 1, 1984. (Disney General Entertainment Content via Getty Images)

Mary Lou Retton, former Olympic Gold Medalist in Women's Gymnastics, looks on during the 2009 Tyson American Cup at the Sears Centre on February 21, 2009 in Hoffman Estates, Illinois.  (Jonathan Daniel/Getty Images)

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Schrepfer did not say what exactly happened to cause the setback but did say that Retton had a "better day" on Wednesday and that she was "just really, really exhausted."

"She is still in ICU. And we're just working through some things as far as her setback goes. So I just wanted to give an update there," Schrepfer said. "She had a better day today, which is great. She is just really, really exhausted."

Gymnast Mary Lou Retton of the United States on the (right end) waves to the fans with her teammates during competition in gymnastics