Answer by taking a quote from the following article:

Born in Oakland, California, Sheila E. is the daughter of Juanita Gardere, a dairy factory worker, and percussionist Pete Escovedo, with whom she frequently performs. Her mother is Creole-French/African mix, and her father is of Mexican origin. Sheila E's uncle is Alejandro Escovedo, and Tito Puente was Escovedo's godfather. She also is niece to Javier Escovedo, founder of seminal San Diego punk act The Zeros.

Prince met Sheila E. at a concert in 1978, when she was performing with her father. After the show he met her and told her that he and his bassist Andre Cymone "were just fighting about which one of us would be the first to be your husband." He also vowed that one day she would join his band. The two would eventually join forces during the Purple Rain recording sessions. She provided vocals on the B-side to "Let's Go Crazy", "Erotic City" in 1984. Though taken under Prince's wing, she proved to be a successful artist in her own right.  In June 1984, she released her debut album The Glamorous Life. The album's title-track single "The Glamorous Life" peaked at number 7 the Hot 100 and also topped the dance charts for two weeks in August 1984. The video for the song would bring three MTV Award nominations for Best Female Video, Best New Artist, and Best Choreography. She also received two Grammy Award nominations for Best New Artist and Best Pop Vocal Performance Female. Her second single "The Belle of St. Mark" charted at number 34 on Billboard Hot 100 and later became NME's "Single of the Week". She also toured as the opening act for Prince's Purple Rain Tour and the duo simultaneously began a brief romantic relationship, while Prince was still seeing Susannah Melvoin, twin sister of The Revolution band member, Wendy Melvoin. They would later become briefly engaged in the late '80s, during Prince's Lovesexy Tour.  In 1985, she released Romance 1600. The lead single "Sister Fate" peaked at number 36 on the R&B charts. The album's second single "A Love Bizarre" became her signature song, peaking at number 11 the Hot 100 and also topped the dance charts. The non-album track "Holly Rock" made its way to live shows and into the film Krush Groove. Sheila later served as Prince's drummer and musical director in his band during the tours from 1987 to 1989. In July 1986, her self-titled album Sheila E. was released. The ballad single "Hold Me" peaked at number 3 on R&B charts. She appeared in four films, Krush Groove with Run-D.M.C., LL Cool J and Blair Underwood in 1985, Prince's concert film, Sign "O" the Times in 1987 The Adventures of Ford Fairlane and Chasing Papi in 2003.

What was Sheila E working on in 1984?
She provided vocals on the B-side to "Let's Go Crazy", "Erotic City" in 1984.