Viral Encephalitis or Meningitis: Given the age and presentation of the patient, a viral infection affecting the brain could lead to confusion. This is a common cause of acute confusion in otherwise healthy individuals.

Substance Intoxication or Withdrawal: Alcohol, drugs, or medication misuse can cause confusion. Given the patient's age, this is a plausible explanation.
Sleep Deprivation: Lack of sleep can significantly impair cognitive function, leading to confusion.
Psychiatric Conditions: Acute psychotic episodes, severe depression, or anxiety disorders can present with confusion.
Metabolic Disorders: Electrolyte imbalances (e.g., hyponatremia, hypernatremia), hypoglycemia, or hyperglycemia can cause confusion.

Stroke or Transient Ischemic Attack (TIA): Although less common in younger individuals, a stroke can cause sudden confusion and is a medical emergency.
Seizures: Post-ictal confusion following a seizure is a critical diagnosis not to miss.
Traumatic Brain Injury: Even minor head injuries can lead to confusion, especially if there's an underlying condition like a subdural hematoma.
Infections: Sepsis, brain abscess, or other severe infections can present with confusion and are life-threatening if not promptly treated.
Carbon Monoxide Poisoning: This can cause confusion among other symptoms and is crucial to diagnose early due to its high mortality rate.

Autoimmune Encephalitis: A rare condition where the body's immune system attacks the brain, leading to confusion and other neurological symptoms.
Prion Diseases: Extremely rare, these diseases (e.g., Creutzfeldt-Jakob disease) cause progressive neurological deterioration, including confusion.
Wilson's Disease: A genetic disorder leading to copper accumulation in the brain, which can cause neurological symptoms including confusion.
Mitochondrial Disorders: Rare genetic conditions affecting the mitochondria, which can lead to a variety of neurological symptoms, including confusion.