Viral Upper Respiratory Tract Infection (URTI): This is the most common cause of acute coughing, often presenting with other symptoms such as sneezing, runny nose, and sore throat. The high prevalence of viral URTIs in the general population makes this the single most likely diagnosis.

Acute Bronchitis: Often follows a viral upper respiratory infection, acute bronchitis can cause a persistent cough. It's more common in smokers or those with underlying respiratory conditions.
Pneumonia: Can present with acute cough, especially if bacterial in origin. Other symptoms might include fever, chest pain, and difficulty breathing.
Allergic Rhinitis: Allergies can trigger coughing, especially in individuals with known allergies or during specific times of the year when allergen levels are high.
Asthma: An asthma exacerbation can cause acute coughing, often accompanied by wheezing and shortness of breath.

Pulmonary Embolism: Although less common, a pulmonary embolism can present with sudden onset of cough and is a life-threatening condition that requires immediate medical attention.
Cardiac Failure: Congestive heart failure can cause a cough, especially if it's worsening or if the patient has a history of heart disease.
Pneumothorax: A collapsed lung can cause sudden, severe cough and is a medical emergency.

Tuberculosis (TB): While less common in many parts of the world, TB can cause a chronic cough but can present acutely in some cases.
Cystic Fibrosis: A genetic disorder that can cause persistent cough due to the production of thick, sticky mucus.
Interstitial Lung Disease: A broad category of diseases that affect the tissue and space around the air sacs of the lungs, which can cause cough among other symptoms.
Foreign Body Aspiration: More common in children, but can occur in adults, especially those with altered mental status or dysphagia, leading to sudden onset of cough.