How to treat cough and throat irritation?

Q: Since 1.5 months I was suffering from cough and throat irritation. Initially I had contacted doctor who advised me to take Azithromycin. However even after completing the course the situation had not improved. The doctor then advised me to take Sparfloxacin. I have completed that course also. ALthough the cough has decreased and no mucous is visible in sputum, I still get cough, especially at night when I lie down, or when exposed to cold weather or drinks, dust or even to goodknight mats. This situation I had not faced before. Moreover the sputum is thick, colorless and foamy but devoid of mucous.I donot understand, is it symptomatic of COPD, asthma? I was not so hyperresponsive earlier to the trigers I had mentioned.Kindly advise what I should do?

A:A persistent cough often follows a viral infection, and may only fade away a few months later. Asthma often presents with only a cough, and diagnosis can be a challenge. Indeed, it is sometimes best to treat a cough as though there was underlying asthma, and assume that this is the correct diagnosis if there is a very good response. Allergy, with low-grade sinusitis or post-nasal drip, can provoke a persisting cough; allergy treatment usually helps. Regurgitation from the stomach can be a cause of coughing without other significant symptoms; characteristically, this worsens when lying down. The commonest obvious cause of a daily cough is airway irritation from smoking or second hand smoke, or from dust, chemicals or allergens in the air. In all cases of apersisting cough, a chest x-ray will be needed to rule out conditions such as tuberculosi or cancer. Sputum evaluation by a laboratory will help make the diagnosis. Finally, a pulmonary physician may have to do a bronchoscopic examination to determine if there is an airway lesion causing the cough.