Hello Productive cough with fever off & on throat pain ,not responding to Azithromycin + benadryl may be due to these reasons , these includes. 1 Asthmatic allergic bronchitis , diagnosis can be confirmed by physical examination by a physician . Usually mite , dust , hay , pollen , fumes, smokes , cotton fiber are responsible for such symptoms . As this is due to allergy and if infection is added may develop expectoration ( sputum). 2 Bronchiectasis is the another most common cause of this type of cough with fever and sputum. Diagnosis can be confirmed by X ray chest with physical examination. 3 Tuberculosis is another most common cause because , throat pain with fever and productive cough with history of illness more than 10 days , indicates tuberculosis . Diagnosis can be confirmed by sputum , blood for C B C , E S R and X ray chest. In my opinion as your father is not responding to antibiotics , consult a physician and get his opinion as described above. Good luck.