Are you adding Epsom salt to the tank water? It will help. See following past discussion on rectal prolapse for more info.
https://www.monsterfishkeepers.com/forums/threads/prolapsed-anus-rectum-in-cichlids.591591/
https://www.monsterfishkeepers.com/forums/threads/prolapsed-anus-rectum-in-cichlids.591591/
