Khloé Kardashian was forced to postpone a book tour appearance in order to undergo tests after stress caused an unknown illness, the reality star said on Twitter.

"Dolls! So sorry I needed 2 re schedule my book signing. I'm sick & dr's orders are that I need to lay low until we narrow down what's wrong. I'll be going for more testing today. I'm very sorry again. Stress can run our bodies down so please everyone take care of yourselves," she tweeted Wednesday.

Kardashian, 31, had been scheduled to appear in Houston on Friday to sign copies of her new book "Strong Looks Better Naked," which came out Nov. 3.

TMZ.com said Wednesday that Kardashian had contracted a staph infection while taking care of her estranged husband, former NBA player Lamar Odom, during his extended hospital stay.

Clarkson's pregnancy

Kelly Clarkson said she loves being a mom, but on Wednesday she told "CBS This Morning" co-host Gayle King that she's been having a difficult times during her second pregnancy.

"I'm familiar with all-day sickness," Clarkson, 33, said on the show. "I have to get IVs and fluids because I get so dehydrated. It's really bad."

On Oct. 23, the singer announced on Instagram that she is expecting a boy. She and her husband, Brandon Blackstock, already have a daughter, River Rose, who was born in June 2014.

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