Temporomandibular Joint (TMJ) Disorder: This condition is characterized by pain and dysfunction of the jaw joint and surrounding muscles. A clicking or popping sound when opening or closing the mouth is a common symptom, which can be perceived as coming from behind the ears due to the proximity of the TMJ to the ear.

Eustachian Tube Dysfunction: The Eustachian tube connects the middle ear to the back of the nose and throat. Dysfunction of this tube can lead to clicking or popping sounds in the ear, especially when swallowing, yawning, or experiencing pressure changes.
Middle Ear Myoclonus: This is a rare condition but can cause clicking sounds due to the contraction of muscles in the middle ear.
Palatal Myoclonus: Although less common, this condition involves the involuntary contraction of one of the muscles in the palate, which can produce a clicking sound that might be perceived as coming from behind the ear.

Giant Cell Arteritis: Although rare, this condition involves inflammation of the blood vessels and can lead to serious complications, including blindness. It may present with jaw claudication and could potentially cause sounds perceived as clicking due to the involvement of the temporal artery.
Vascular Malformations or Aneurysms: Abnormalities in the blood vessels behind the ear could potentially cause unusual sounds, including clicking. These conditions are serious and require prompt medical attention.

Patulous Eustachian Tube: A condition where the Eustachian tube remains open, leading to autophony (hearing one's own internal sounds unusually loudly) and potentially clicking sounds.
Stapedial Myoclonus: An extremely rare condition involving the involuntary contraction of the stapedius muscle in the middle ear, leading to clicking sounds.
Nasopharyngeal or Sinus Tumors: Although very rare, tumors in the nasopharynx or sinuses could potentially cause Eustachian tube dysfunction or other issues leading to perceived clicking sounds behind the ears.