AceShowbiz -

Khloe Kardashian had to cancel a book tour appearance due to mysterious illness. The event to promote her new book "The Strong Looks Better Naked" which was supposed to take place on Wednesday, November 18 is rescheduled per doctor's orders.

The 31-year-old reality TV star has taken to Twitter to address the event cancellation. "Dolls! So sorry I needed 2 re schedule my book signing," so she tweeted, "I'm sick &dr's orders are that I need to lay low until we narrow down what's wrong."

She added in another post, "Ill 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 also thanked her fans for their support, writing, "I'm reading all of your tweets + messages on my Facebook.... seriously u guys give me strength! I love and appreciate you more than u know."

A source tells E! News that "Khloe has experienced fever, fatigue, and swollen glands. She has an infection but hasn't been diagnosed yet." Another source adds that the star "has an minor infection and is being treated by her doctors. She is run down as she has been burning the candle at both ends. She will be fine but needs some rest."

According to TMZ, Khloe has a serious staph infection which she contracted while she's taking care of her estranged husband Lamar Odom in the hospital. The site goes on noting how serious her illness is, reporting that the "Keeping Up with the Kardashians" cast member has a lesion on her leg which became incredibly painful. She's also sweating profusely with intermittent chills.

A source claims, "It's so scary. She's so sick."