Question:

Can a Jew come back as a gentile in another gilgul and also can a gentile come back as a jew in another gilgul?

Answer:

Rav Chaim Vital1)Shar Hagilgulim Hakdamah 22 says that Bilaam HaCasha was reincarnated as a rock and then after that as Nevel HaCarmeli (a jew). He also says at the very end of that same section that a man who has biyah with a niddah is reincarnated as a gentile woman.

References   [ + ]

1. Shar Hagilgulim Hakdamah 22