Credit: Jon Kopaloff/FilmMagic

Who says Selena Gomez isn't ready to get back on stage?

The singer-actress was rushed to an L.A. hospital on Thursday night when she reportedly complained of nausea and a severe headache. But on Monday, the 18-year-old told her fans via Twitter she was "feeling much better."

"Thank you all for being so understanding," she said. "Can't wait to see you all today at Santa Monica Place for the Monte Carlo kickoff!" (Gomez has the first show of her 10-city tour on Monday, rescheduled from Friday after her Thursday drama.)

One insider told Us Weekly that Gomez collapsed from food poisoning coupled with exhaustion. But before heading to the hospital, Justin Bieber's love was "nothing but professional" during her appearance on the Tonight Show with Jay Leno.

"She did a backstage interview and hung out with Jim Carrey after the show. The Tonight Show people didn't even know she wasn't feeling well," the insider added.

Gomez stayed in the hospital Thursday night for observation. She paid a return visit on Saturday.