Benign Paroxysmal Positional Vertigo (BPPV): This condition is characterized by brief, episodic vertigo triggered by head movements, and it can also cause tinnitus. Its high prevalence and the fact that it often presents with sudden onset make it a likely candidate for acute tinnitus.

Middle Ear Infection: Acute otitis media can cause tinnitus due to the inflammation and fluid buildup in the middle ear. The sudden onset of tinnitus, especially if accompanied by ear pain or fever, suggests this diagnosis.
Eustachian Tube Dysfunction: Problems with the Eustachian tube, which regulates air pressure in the ears, can lead to tinnitus. This condition can be triggered by allergies, colds, or sinus infections, making it a common cause of acute tinnitus.
Noise-Induced Hearing Loss: Exposure to loud noises can suddenly cause tinnitus, making this a likely diagnosis in individuals who have recently been in loud environments without proper ear protection.

Acoustic Neuroma: Although rare, this benign tumor on the nerve connecting the inner ear to the brain can cause tinnitus. It's crucial to diagnose early due to potential complications and the need for timely treatment.
Stroke or Transient Ischemic Attack (TIA): In some cases, tinnitus can be a symptom of a stroke or TIA, especially if it's sudden, unilateral, and accompanied by other neurological symptoms. Missing this diagnosis could be fatal.
Meniere's Disease: This disorder of the inner ear can cause episodes of vertigo, tinnitus, hearing loss, and a feeling of fullness in the ear. While not immediately life-threatening, early diagnosis is important for managing symptoms and preventing further hearing loss.

Autoimmune Inner Ear Disease: This condition involves the immune system attacking the inner ear, leading to sudden hearing loss and tinnitus. It's rare but requires prompt treatment to preserve hearing.
Ototoxicity: Certain medications and chemicals can damage the ear, causing tinnitus. This is a rare cause but should be considered, especially in patients recently started on new medications known to be ototoxic.
Vascular Malformations or Fistulas: Abnormal connections between arteries and veins in the head or neck can cause tinnitus. These conditions are rare and often require specialized imaging for diagnosis.