More than two months ago I had what was either a cold or a mild case of the flu. I recovered from it within 3-4 days. But one thing that has lingered since then (and which I think started immediately prior to the cold) was an occasional productive cough. Mucus is usually white or yellowish, and cough is infrequent--most often at night, but during an episode I might find myself coughing very hard for a few minutes. I told my primary physican about it earlier this month and she was not concerned--she listened to my lungs and said they sounded fine. But since it's been two months, I wonder if I might be dealing with some kind of persistent infection that may not really be interfering with breathing, but still may be a cause for concern. I do have asthma, but it's been under good control since my cold.