Costochondritis: This condition, also known as Tietze's syndrome, is characterized by inflammation of the cartilage that connects the ribs to the breastbone, leading to chest pain. The pain can be sharp and stabbing, is often localized to one side, and can be exacerbated by movement or deep breathing. The association with nervousness could be due to the pain itself causing anxiety or due to the patient's anxiety exacerbating the perception of pain.

Musculoskeletal Pain: Strains or pulls in the muscles between the ribs (intercostal muscles) or in the chest wall can cause sharp pains that are worse with movement or deep breathing. The lack of shortness of breath and the pain not being worse on exertion supports this diagnosis.
Anxiety or Panic Disorder: The patient's report of nervousness associated with the pain suggests that anxiety could be a contributing factor. Anxiety and panic disorders can manifest with physical symptoms, including chest pain, that are not related to cardiac issues.
Gastroesophageal Reflux Disease (GERD): GERD can cause chest pain that is often described as burning and can be worsened by lying down or eating certain foods. However, the sudden onset and lack of gastrointestinal symptoms make this less likely.

Pulmonary Embolism (PE): Although the patient does not report shortness of breath, PE can present with sudden onset chest pain and must be considered due to its high mortality rate if missed. The absence of typical symptoms does not rule out PE.
Myocardial Infarction (MI): While less common in a 32-year-old without risk factors, MI can occur at any age and must be ruled out due to its potential for severe consequences. The pain profile does not perfectly match typical MI pain, but atypical presentations can occur.
Pneumothorax: A spontaneous pneumothorax can cause sudden onset chest pain and can be life-threatening if not promptly treated. The lack of shortness of breath does not exclude this diagnosis, especially if the pneumothorax is small.

Pericarditis: Inflammation of the pericardium, the sac surrounding the heart, can cause sharp chest pain that may improve with sitting up and leaning forward. It is less common and might not be the first consideration without additional symptoms like fever or a pericardial friction rub.
Esophageal Spasm or Rupture: These conditions can cause severe chest pain but are less common. Esophageal rupture is a medical emergency and would typically present with severe pain and potentially vomiting or difficulty swallowing.