Concussion with persistent post-concussive symptoms: Given the history of head injury with loss of consciousness and the presence of symptoms such as vomiting, headache, loss of balance, and coordination, despite a non-diagnostic CT head, this diagnosis is highly plausible. The symptoms are consistent with post-concussive syndrome, which can occur after a concussion.

Basilar skull fracture: The presence of ear pain, vomiting, and loss of balance could suggest a basilar skull fracture, especially if there was trauma to the base of the skull. This would require further imaging, such as a CT scan with thinner slices or an MRI, for diagnosis.
Labyrinthine concussion: This condition, resulting from trauma to the inner ear, could explain the loss of balance and coordination, as well as the ear pain. It's a consideration given the mechanism of injury and the symptoms presented.
Cerebral vasospasm or post-traumatic migraine: These conditions could explain the headache and other symptoms. However, they might be less likely without other specific findings or a history suggestive of migraine.

Intracranial hemorrhage (despite initial NAD CT): Although the initial CT head was non-diagnostic, the patient's age, the mechanism of injury, and the fact that they are on a direct oral anticoagulant (DOAC) increase the risk of developing an intracranial hemorrhage. Repeat imaging or close observation might be necessary, especially if symptoms worsen or new symptoms develop.
Cervical spine injury: Given the mechanism of injury that caused a head injury, there's a risk of associated cervical spine injury, which could explain some of the symptoms like loss of balance and coordination. This is a critical diagnosis not to miss due to the potential for spinal cord injury.
Temporal bone fracture: This could explain the ear pain and might be associated with other complications like facial nerve paralysis or cerebrospinal fluid leak. Given the potential for serious complications, it's a diagnosis that should not be missed.

Perilymphatic fistula: A rare condition that could result from trauma to the ear, leading to symptoms like vertigo, hearing loss, and ear fullness. It's less likely but could be considered if other diagnoses are ruled out and the patient has specific auditory or vestibular symptoms.
Superior canal dehiscence syndrome: Another rare condition that could result from head trauma, characterized by sound- or pressure-induced vertigo, and hearing loss. It would be a consideration in the differential if the patient presents with unique auditory symptoms in conjunction with vertigo.