Apparently, one of the backup performers accidentally struck Gaga in the head while removing a set prop from the center stage during one of the states changes. At the time Lady Gaga was holding a fake machine gun and she rubbed her head and staggered off the stage. She came back out and finish the concert and will keep on with her world tour.
Lady Gaga’s makeup artist
Tara Savelo wrote Monday on Twitter: "Gaga has a concussion but she is going to be okay … cant believe she finished the show."