Foreshadowing

"But I do love thee! And when I love thee not, Chaos is come again." (III.iii. 92-93)

Othello has been mild mannered throughout the first 2 acts, but this seems to be his breaking point. Iago continues to raise his suspicions of Desdemona's unfaithfulness. Although some are misunderstandings and some are blatantly false, Othello is unaware. I think this foreshadows the upcoming chaos that will ensue when Iago finally completes every aspect of his plan. Othello's anger will get the best of him and ultimately Iago will have his desired job and Othello and Desdemona will split up. Another instance of foreshadowing is when Othello has head pains and Iago torments his lack of sleep, because both of those point to his epilepsy. Seizures can be caused by lack of sleep. I don't know if that is what will cause Othello's seizure and maybe even death, but I think his epilepsy will play into the plot soon.