Differential Diagnosis for Severe Pain behind the Right Ear

Single most likely diagnosis

• Temporalis muscle strain or temporomandibular joint (TMJ) disorder: The location of the pain (posterior to the ear lobe, 1.5 inches superior to the angle of jaw) and tenderness on palpation are consistent with a TMJ disorder or temporalis muscle strain, which can cause severe pain and are relatively common.

Other Likely diagnoses

• Mastoiditis: Although the patient has no history of middle ear infection, mastoiditis can occur without preceding otitis media. The pain location and sudden onset could be indicative of mastoiditis, especially if there's any sign of infection.
• Occipital neuralgia: This condition involves the nerves that run from the base of the skull to the scalp and can cause severe pain behind the ear, which fits the patient's symptoms.
• Cervicogenic headache: Referred pain from the cervical spine can cause pain in the area behind the ear, and the rapid onset and nausea could support this diagnosis.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

• Temporal arteritis (Giant Cell Arteritis): Although less common, especially in a 30-year-old, temporal arteritis can cause severe headache and pain in the temporal region. Missing this diagnosis could lead to serious complications, including vision loss.
• Meningitis: The sudden onset of severe pain and nausea could be indicative of meningitis, an infection of the protective membranes covering the brain and spinal cord. This condition is medical emergency.
• Stroke or Transient Ischemic Attack (TIA): Pain is not a typical presenting symptom, but in rare cases, stroke or TIA can manifest with unusual symptoms, including severe headache or pain.

Rare diagnoses

• Eagle syndrome: This condition involves an elongated styloid process or calcified stylohyoid ligament, which can cause sharp, stabbing pain in the side of the throat or the ear. It's a rare condition but could fit the patient's symptoms.
• Osteomyelitis of the temporal bone: A rare infection of the bone that could cause severe pain in the area behind the ear, though it would typically be accompanied by other signs of infection.
• Neoplasm (tumor) in the temporal region: Although very rare, a tumor could cause localized pain and should be considered if other diagnoses are ruled out and the pain persists or worsens over time.