All in My Head ( Flex ) " is a song recorded by American group Fifth Harmony , featuring vocals by rapper Fetty Wap , for their second studio album , '' 7/27 '' ( 2016 ) , which was released on May 27 , 2016 . It was produced by Stargate and Brian " Peoples " Garcia with additional production by Sir Nolan . Musically , " All in My Head ( Flex ) " is a reggae-trap song backed by synths , percussion , and guitar , containing an interpolation of the 1995 song " Flex " by Mad Cobra . The song was released as second single after a special encore performance on Xfinity following the 2016 Billboard Music Awards on May 22 , 2016 . The single was serviced to rhythmic contemporary radio stations in the United States on May 31 , 2016
2016 Billboard Music Awards
2016 Billboard Music Awards
All in My Head (Flex)