Roger Karnbad/Celebrity Photo
09/16/2009 AT 07:50 PM EDT
She's not sure exactly when it happened – probably during a rehearsal – but pop star Pink
knows this much for sure: "It hurts."
Pink, 30, has suffered a separated shoulder, her rep tells PEOPLE, and was unable to do the aerial parts of her trapeze-heavy show in Seattle on Tuesday night.
Despite her injury, the singer has decided not to cancel any of her upcoming concert dates. "The show must go on," adds her rep. Next stop for Pink's Funhouse Tour is LA's Staples Center on Friday.
Pink wrote about the pain on her Twitter page
, saying she never really knew what boyfriend Carey Hart went through when he broke his collarbone. "Now I [know]," she says.