The "Catch Me When I Fall" singer, on the road to support her chart-topping I Am Me--and to prove to the world that she really can sing--remains in an undisclosed hospital, publicist Rob Shuter said Friday.
News of the hospitalization was first reported by Us Weekly, which said Simpson had just finished a rendition of the hit single "Boyfriend" before telling the audience that she felt sick. "I love you guys," she said before exiting, only to collapse moments later in an elevator. She was immediately taken by ambulance to the hospital, per the magazine.
There's been no official word on the cause of the fainting spell, but Us Weekly quotes an unnamed source close to the family citing exhaustion as the reason for her collapse.
"She's wanted to prove over and over to her fans that she can perform live after what happened on SNL last year," the magazine quotes
Simpson, 21, has been promoting I Am Me for the better part of two months, including a return to the scene of the mime on Saturday Night Live, a string of concert dates and several TV and magazine interviews.
She has made headlines in recent weeks for her early-morning meltdown at a Toronto McDonald's (featuring her writing on the counter and telling an autograph-seeking fan to "kiss my foot") and her confession to Cosmopolitan that she suffered a "minor" eating disorder a decade ago when she was taking ballet lessons. Ashlee has also been helping sister Jessica work through her separation from Nick Lachey.
Her family is reportedly waiting for an official diagnosis before deciding whether to travel to Japan.
Meantime, Ashlee's appearance on Monday's Radio Music Awards in Las Vegas has been canceled.