although all of those symptoms suggesting common cold, but it shouldn't continue for more than 10 days unless it is complicated with ''sinusitis'' which is an inflammation of air sinuses (pockets) around the nose..or chest infection. This may explain the prolonged duration, associated headache and thick secretions. in this situation you should see a doctor to ascertain the diagnosis and may prescribe an appropriate antibiotic.
These are normal signs of flu and they should disappear with time as long as you are on medication. This could also be accompanied by some malaria or typhoid and so, you will need to see a doctor for proper diagnosis.
You havent heard? There is a flu EPIDEMIC sweeping the US! Influenza B is making people sick for up to a week or more. Its more of a respiratory flu tho. Maybe you have a touch of more than one strain. So yeah. Its pretty normal right now. Rest and stay hydrated.