Rihanna I'm Sick as Hell ... but I'm Still Smilin'

11/3/2011 10:00 AM PDT

Before doctors advised Rihanna to cancel her concert in Sweden last night, the singer was seen walking around her hotel yesterday ... wearing a smile, even though she felt like crap.

Rihanna has been battling a nasty case of the flu ... and after this photo was taken, she canceled her second show this week because of exhaustion.

According to reports, organizers are working to reschedule the shows.