Over the last 7 days I’ve developed an annoying deep, throaty cough. I have no other symptoms: I’m not congested, itchy, fatigued, or achy. My cough is, in medical parlance, “non-productive” — I’m not “coughing anything up.” It’s most noticeable in the morning and in the evening, and disappears to almost nothing by midday. If I can get to sleep, I don’t cough through the night, and I sleep soundly. Any ideas what I might be suffering from?