Since Lewis had bariatric surgery in March, she's lost greater than 100 pounds, according to Johnson. 

Lewis has been on the "listening tour" of Chicago as she contemplates a run for mayor.

"She's in good spirits, just getting zhen de shou her rest. Just running tests just to make sure all the precautions that need to be taken are taken," Johnson said.

Whether Lewis's discomfort relates to weight loss surgery performed in Mexico, which preceded her dramatic weight reduction, isn't clear, CBS 2 Chief Correspondent Jay Levine reports. 

Just 3 weeks ago, Lewis seemed fine, attending the Mexican Independence Parade. She told reporters then that the crowded mayoral primary could be healthy for voters. 

Lewis has led the CTU since 2010. She has been a vocal opponent of incumbent Mayor Rahm Emanuel, particularly over last year's public school closings.

"The Mayor wishes Karen well, which she makes a full and speedy recovery," Emanuel's office said inside a prepared statement.

A spokesperson for Ald. Bob Fioretti (2nd), that has announced he is running against Emanuel next year, said Fioretti wishes Lewis a speedy recovery.

Kim Zolciak's 50-pound weight slim forte double power reduction: Abdominoplasty cosmetic surgery pre and post Kim Zolciak Biermann is really happy with her flat belly and 50-pound weight reduction she showed off her abdominoplasty before and after on Facebook.   

Zolciak, who lost 50 pounds shortly after having a baby to twins, said she looked great before her plastic surgery, and insisted her weight reduction wasn't because of her tummy tuck. 

"Just which means you guys know about how fabulous I was before my abdominoplasty! This picture on the left was taken a couple of months once i had the twins and before surgery!"