Cough/throat irritation (no sore throat or any other symptoms), sometimes green mucus comes out, dr said lungs clear. over 3 weeks duration. what is?

Dr. can check throat: Throat symptoms can be from a strep throat infection (antibiotics are needed), a cold or other virus (antibiotics usually not used), allergies or irritants, sinusitis, stomach reflux when asleep, etc... Usually, a person sees the doctor if the throat is bothersome, recurrent, or doesn't go away quickly (mainly to check for strep and review the story to see if sinusitis or reflux might be a cause).