I have a heavy cough with yellow phlegm my head pounds with each cough. Now I'm losing my voice. No other symptoms, what could this be?

Cough. Cough with sputum production is bronchitis. Paroxysmal coughing can lead to headache and chest/abdominal muscle discomfort. Headache could also be a symptom of sinusitis which can make cough and sputum production worse. If symptoms don't improve with otc remedies or worsen (fever/ chills/nausea with vomiting which precludes you from being able to stay hydrated/etc)-see a doctor!