the interjection or complaining sound of someone who is in pain (see Molina)
Alonso de Molina:
he o. interjection del que sequexa con dolor. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 30r. col. 1. Thanks to Joe Campbell for providing the transcription.