Lung Cancer with Mediastinal Involvement: This condition can cause unilateral neck swelling due to metastasis to lymph nodes, dizziness and shortness of breath from compression or invasion of major airways, chest pain from tumor invasion into the chest wall or mediastinum, and hoarse voice from recurrent laryngeal nerve compression.

Thyroid Cancer: Similar to lung cancer, thyroid cancer can cause neck swelling, and if it invades or compresses nearby structures, it can lead to the other symptoms.
Deep Vein Thrombosis (DVT) with Pulmonary Embolism (PE): While DVT typically causes leg swelling, a large PE can cause sudden onset of shortness of breath and chest pain. If there's associated neck swelling, it might be due to a separate condition, but the combination of symptoms could occur in a patient with multiple issues.
Tuberculosis (TB): TB can cause a wide range of symptoms including neck swelling (from lymphadenopathy), chest pain, shortness of breath, and potentially hoarseness if there's laryngeal involvement.

Aortic Dissection: Although it might not directly cause unilateral neck swelling, an aortic dissection can lead to severe chest pain and shortness of breath. If the dissection involves the aortic arch, it could potentially cause hoarseness due to compression of the recurrent laryngeal nerve. This is a medical emergency.
Pulmonary Embolism: A large PE can cause sudden onset of shortness of breath and chest pain, potentially with dizziness. While neck swelling is not a typical symptom, in a patient with multiple conditions, it's crucial not to miss a PE.
Carotid Artery Dissection: This can cause neck pain and swelling on the side of the dissection, along with neurological symptoms. If the dissection compromises blood flow, it could lead to dizziness. It's less likely to cause hoarseness or shortness of breath directly but is a critical diagnosis due to the risk of stroke.

Castleman Disease: A rare lymphoproliferative disorder that can cause lymphadenopathy (potentially unilateral neck swelling), and systemic symptoms. It's less likely to cause the full spectrum of symptoms listed but could be considered in a differential diagnosis.
Relapsing Polychondritis: An autoimmune disorder that can cause inflammation of cartilaginous structures, including the trachea and larynx, potentially leading to hoarseness, shortness of breath, and chest pain. Neck swelling could occur if there's significant inflammation or associated lymphadenopathy.
Sarcoidosis: While more commonly causing bilateral hilar lymphadenopathy, sarcoidosis can cause unilateral neck swelling and a wide range of systemic symptoms, including those affecting the lungs and potentially the nerves, leading to hoarseness.