06/14/2011 at 07:15 AM EDT
Nothing can heal a teen pop star faster than a shopping mall filled with screaming fans.
appears to be on the mend, taking the stage Monday for a Santa Monica Place show that had to be rescheduled from Friday due to her hospitalization
"I want to thank you so much for coming," Gomez, 18, told more than 500 young fans at the outdoor mall. "If you guys came on Friday, I'm so sorry that I couldn't be here. ... I love you guys very much."
Asked by reporters for the cause of her hospitalization, she said, "I was just very malnourished, so I was low on iron and exhausted."
Showing no signs of those health problems, an energetic Gomez performed "Who Says" and "A Year Without Rain" and bantered with the crowd, telling the fans, "I do feel better!"
Additional reporting by GABRIELLE OLYA