It looks like Selena Gomez is finally on the mend after spending a long weekend at the hospital. The singer, who was rushed to the hospital on the evening of June 9 following an appearance on 'The Tonight Show,' was back onstage Monday morning for a rescheduled concert at a mall in Santa Monica, Calif.

According to a report from PEOPLE, the singer was suffering from malnourishment, which caused her iron levels to dip dangerously low. This is what was causing the severe headaches and nausea she was experiencing last Thursday. She told reporters Monday, "I was very malnourished, so I was low on iron and exhausted."

During her outdoor show at the mall on Monday, 18-year-old Gomez thanked the crowd of 500+ fans, saying, "I want to thank you so much for coming. If you guys came on Friday, I'm so sorry that I couldn't be here ... I love you guys very much."

A smiley Gomez gave a high-energy performance for her fans, exclaiming "I do feel better!" at one point during the show. We just hope that she doesn't exert herself too much, as the malnourishment and exhaustion she experienced were probably caused by her arduous career activities (dancing, acting, singing, fighting off Justin Bieber's crazed fans).

Please be sure to rest up and take care of yourself first and foremost, Selena! We would hate to see you get sick again!

Watch Selena Gomez Talk to the Press After Her Show in Santa Monica