Acute Bronchitis: This condition is characterized by inflammation of the bronchial tubes, often resulting from a viral or bacterial infection. Symptoms include cough with thick yellow sputum, arthralgia, myalgia, and can sometimes affect the voice due to prolonged coughing or postnasal drip. The combination of upper respiratory symptoms, presence of thick yellow sputum, and systemic symptoms like arthralgia and myalgia makes acute bronchitis a leading consideration.

Influenza: Influenza infections can present with upper respiratory symptoms, myalgia, arthralgia, and can lead to secondary bacterial infections that cause the production of thick yellow sputum. The change in voice could be due to laryngitis, a known complication of influenza.
Pneumonia: While pneumonia primarily affects the lower respiratory tract, it can present with upper respiratory symptoms initially, especially in cases of viral pneumonia or early stages of bacterial pneumonia. The presence of thick yellow sputum and systemic symptoms supports this diagnosis.
Sinusitis: Sinus infections can cause upper respiratory symptoms, including thick yellow nasal discharge (which might be coughed up as sputum), facial pain, and can lead to systemic symptoms like myalgia and arthralgia. The change in voice could be due to postnasal drip.

Pertussis (Whooping Cough): Although less common due to vaccination, pertussis can cause severe cough with thick sputum, systemic symptoms, and can affect the voice. It's crucial to consider this diagnosis, especially in unvaccinated or under-vaccinated individuals, due to its contagious nature and potential for severe complications.
Tuberculosis (TB): TB can present with chronic cough, sputum production, systemic symptoms like myalgia and arthralgia, and can affect the larynx, leading to voice changes. Although less likely, TB is a critical diagnosis not to miss due to its public health implications and the need for specific treatment.
Lung Cancer: In rare cases, lung cancer can present with symptoms mimicking upper respiratory infections, including cough with sputum production and systemic symptoms. A change in voice could indicate laryngeal involvement or compression of the recurrent laryngeal nerve. This diagnosis is critical to consider, especially in smokers or those with a significant smoking history.

Sarcoidosis: This autoimmune disease can affect the lungs and cause respiratory symptoms, including cough and sputum production. Systemic symptoms like myalgia and arthralgia are common, and laryngeal involvement can lead to voice changes. Sarcoidosis is less likely but should be considered in the differential diagnosis, especially if other diagnoses are ruled out.
Histoplasmosis: A fungal infection that can cause respiratory symptoms, including cough with sputum production, and systemic symptoms. Laryngeal involvement is rare but possible, leading to voice changes. This diagnosis is more likely in individuals who have been exposed to bird or bat droppings.