The singer and actress reportedly decided to get tested for strep throat after complaining of a sore throat, E! Online reports.
A source told E! that Gomez ended a recording session earlier than planned yesterday "because her throat was bothering her."
"Also, her stepfather has had bronchitis, so she wanted to be extra careful to make sure she wasn't getting it, too," the source added.
According to TMZ, doctors don’t believe Gomez has strep throat, but a definitive diagnosis cannot be made until her test results come back in a few days.
Perez Hilton suggests that Gomez's recent recording sessions with Taylor Swift and Miley Cyrus this weekend could have strained her voice.
Gomez’s hospital visit follows a night of celebrating at an American Music Awards after-party until well after midnight.
Selena was reportedly spotted holding hands with her ex-boyfriend Justin Bieber at the party and later attended a private after-party hosted by Bieber and his manager Scooter Braun at Bootsy Bellows in Hollywood.
Bieber took home three awards at the AMAs, for artist of the year, favorite pop/rock male artist, and favorite pop/rock album.