Can it be that she is the dothraki crone that sang when Daenarys ate that horse heart? They sure look much alike and the High priestess said in season 6 that she remembered very well this scene.
Well, it is not the same actress since Souad Faress's entry on IMDB says she is only in Season 6. But there is a possibility that it is the same character but the show used a different actor. Not enough info in the show to know either way.