I have had a cough for 2 months. started out as a dry cough but now producing clear/yellow phlegm. chest x - ray clear.

Lots of possibles: Treat for GERD, allergies, asthma, post-nasal drip. Look out for a new ACE inhibitor med, exposure to pertussis, smoking history, nasal polyps, CHF, skin rash, aspiration, post-viral residue. Avoid spicy foods, tomatoes, citrus. Consider spirometry, CT chest. Maybe treat with inhaled steroids/anticholinergics, Tessalon, codeine, neurontin, or steroids. You may just need to wait another week.