Fluoxetine-induced tinnitus: This is the most likely cause, as fluoxetine, an SSRI, is known to cause tinnitus as a side effect in some patients. The timing of the onset of tinnitus two weeks after starting fluoxetine supports this diagnosis.

Idiopathic tinnitus: This is a common condition where the cause of tinnitus is unknown. It can occur in anyone, regardless of medication use.
Hearing loss: Age-related hearing loss or other forms of hearing impairment can cause tinnitus. Given the patient's age, this is a plausible diagnosis.
Middle ear problems: Issues such as otosclerosis, middle ear infections, or a buildup of earwax can lead to tinnitus.
Ototoxicity from other medications: If the patient is taking other medications known to be ototoxic (e.g., certain antibiotics, aspirin), these could contribute to tinnitus.

Acoustic neuroma: A rare, benign tumor on the nerve connecting the inner ear to the brain. Although unlikely, missing this diagnosis could have significant consequences, including hearing loss and neurological deficits.
Meniere's disease: A disorder of the inner ear that can cause tinnitus, vertigo, and hearing loss. Early diagnosis is crucial for effective management.
Temporal bone fractures: Trauma to the temporal bone can cause tinnitus, among other symptoms. This would be an important diagnosis to consider, especially if there's a history of recent head injury.

Autoimmune inner ear disease: A rare condition where the immune system attacks the inner ear, leading to tinnitus and hearing loss.
Vascular malformations: Abnormalities in blood vessels, such as arteriovenous malformations, can cause tinnitus due to abnormal blood flow.
Neurological disorders: Certain conditions like multiple sclerosis, Lyme disease, or syphilis can cause tinnitus, although these would be uncommon presentations.