Musculoskeletal strain or costochondritis: This is often the most common cause of chest pain with arm tightness in a young adult, especially if there's a history of recent physical activity or trauma. The pain is typically sharp and localized to the chest wall or the area around the ribs.

Anxiety or panic disorder: These conditions can cause chest pain and sensations of tightness or discomfort in the arms, often accompanied by other symptoms like palpitations, shortness of breath, and fear of losing control.
Gastroesophageal reflux disease (GERD): GERD can cause chest pain that may radiate to the arms, especially after eating or at night, due to stomach acid flowing back into the esophagus.
Precordial catch syndrome: This condition involves sharp, stabbing chest pain that can radiate to the arms, often worsened by deep breathing or movement.

Myocardial infarction (MI) or acute coronary syndrome: Although less common in young females, MI can occur, especially with risk factors like smoking, hypertension, or a family history of early heart disease. The pain is typically described as a heavy, squeezing sensation.
Pulmonary embolism (PE): Sudden onset of chest pain and shortness of breath, possibly accompanied by arm pain, could indicate a PE, which is life-threatening and requires immediate medical attention.
Aortic dissection: Severe, tearing chest pain that radiates to the back or arms can be a sign of an aortic dissection, a medical emergency.

Tietze's syndrome: A rare condition characterized by inflammation of the cartilages and surrounding tissues of the ribs, leading to chest pain and swelling.
Spinal disc disease or thoracic outlet syndrome: These conditions can cause arm pain and, less commonly, chest pain due to nerve compression or irritation.
Pericarditis: Inflammation of the pericardium, the sac surrounding the heart, can cause sharp chest pain that may improve with sitting up and leaning forward, occasionally radiating to the arms.