(Cover) - EN Showbiz - Selena Gomez is undergoing tests in hospital after being rushed there last night.

The 18-year-old singer was taken to a medical centre in Los Angeles after appearing on UK talk show host Jay Leno's programme. She felt sick and had a severe headache, and even felt unwell during the interview.

"Last night after Selena's appearance on The Tonight Show she wasn't feeling well and was taken to the hospital," her spokesman told MailOnline.

"She is currently undergoing routine tests."

The cause of Selena's illness remains unknown.

During the programme she appeared relaxed and happy. The singer discussed her romance with Canadian star Justin Bieber, revealing he has met her mother and they get along well.

She also spoke about her relationship with her mom Mandy, revealing they are incredibly close. Mandy raised her on her own and is also an actress, which sometimes caused friction between mother and daughter as Selena didn't always approve of her mom's roles.

"She was an actress too but on stage. I loved to go watch my mom it was my favourite to watch her rehearse for plays," Selena explained. "She did this one play where she had to sing Santa Baby to Santa Claus on stage and kiss him. I was about seven and I was livid she kissed Santa Claus because I wanted her to be with my dad and I was very mad that this happened." (C) Cover Media