Acute Coronary Syndrome (ACS): This is a leading cause of chest discomfort and shortness of breath, especially if the symptoms are worsening over time. The gradual worsening of symptoms could indicate a progression towards a myocardial infarction (heart attack).

Pneumonia: An infection in the lungs that can cause both shortness of breath and chest discomfort, which can worsen over time if not treated.
Pulmonary Embolism (PE): A blood clot in the lungs that can cause sudden onset of shortness of breath and chest pain, which may worsen as the condition progresses.
Asthma or Chronic Obstructive Pulmonary Disease (COPD) Exacerbation: For patients with a history of asthma or COPD, an exacerbation can lead to worsening shortness of breath and chest discomfort.
Gastroesophageal Reflux Disease (GERD): Can cause chest discomfort that may be mistaken for cardiac issues, though it less commonly causes shortness of breath.

Pulmonary Embolism (PE): Although listed as a likely diagnosis, it's crucial to not miss PE due to its high mortality rate if untreated.
Aortic Dissection: A tear in the aorta that can cause severe chest pain and shortness of breath, often described as tearing or ripping. It's less common but highly lethal if not promptly diagnosed and treated.
Cardiac Tamponade: Fluid accumulation in the sac around the heart that can compress the heart and impede its function, leading to shortness of breath and chest discomfort.

Pneumothorax: Air in the space between the lungs and chest wall, which can cause shortness of breath and chest pain, especially if it's a large pneumothorax.
Lymphangitic Carcinomatosis: Spread of cancer to the lymphatic vessels in the lungs, which can cause shortness of breath and chest discomfort, though it's much less common.
Sarcoidosis: An inflammatory disease that can affect the lungs and cause symptoms like shortness of breath and chest discomfort, though its presentation is often more gradual and less acute.