Sarah, one of your pediatric patients complains of pain in her right ear. Her mother tells you that she had repeated ear infections when she was younger. However, tubes were placed through both eardrums (myringotomy) about a year ago and since then Sarah has not had another infection. In fact, Sarah had a follow-up visit with her ENT physician two days ago and everything was fine. Your examination of the oral cavity yields nothing remarkable other than for inflammation of the gingiva due to eruption of the right mandibular second molar. What is the likely cause of Sarah's deep ear pain and WHY?