Sky Ferreira -- Blood Flows During Miley Cyrus Concert

Sky Ferreira got off on the wrong foot Thursday night at Miley Cyrus' "Bangerz" concert in Anaheim ... gushing blood as she performed.

Ferreira tripped and fell during her first song, slicing open her shin. She says she had no idea she was injured during her entire performance.

The singer was loaded onto a stretcher and taken to the hospital ... where doctors sewed her up like a rag doll ... with 60 stitches.

Ferreira is now back in action ... sporting a very uncool bandage around her leg. But the show must go on.