Head Cold, Cough, Running Nose, Throat Pain. Taking Nyquil. History Of Sinus Issues. Treatment?

Four weeks ago I came down with a severe head cold, cough , post nasel drip and runny nose, throat irritation . Fairly well, but not completely cleared up after three weeks, I took Nyquil to control the symptoms (very effective). I still have minor sinus issues (slight runny nose), dry non productive cough, cough worsens with exertion or bending over (as if to pick something up). Appitite fair, though taste of food is more bland.