'My Baby Daddy' B-Rock and the Bizz Member Paul Costict Dead at 57

Paul Costict, one of the original members of the rap group B-Rock and The Bizz -- famous for the single "My Baby Daddy" -- is dead ... TMZ has learned.

Paul died unexpectedly Saturday at his home in Norfolk, VA ... according to a family member. The cause of death is unclear.

While it's unclear exactly how he died, the family member tells us they spoke to Paul Wednesday, he seemed to be in good spirits ... but mentioned recently being sick.

As hip hop fans may know ... B-Rock and The Bizz are a one-hit wonder, thanks to their 1997 single, "My Baby Daddy," which peaked at No. 10 on the Billboard charts back in the day.

The song earned gold certification and Paul eventually ended up in a bitter dispute over his gold album with his ex-wife, Lasancious ... the exes fought over his plaque in a TV episode of "Divorce Court."

In addition to being a member of the band, we're told Paul was also the group's road manager.

Fellow band member Thaddeus "T-Bird" Maye grew up with Paul in Alabama and is remembering him as "a very funny and Kool brother."

Paul was 57.