itchy throat and coughing

I feel that my doctor isn't helping so i figure this place will give me better assistance.  I've been coughing for 3 months now.  I went to see my doctor (general practice) about the problem and he said i have PND (Post Nasal Driping).  He gave me a handful of Zyrtec and prescibe me a bottle of Codeine 300-10.  I've been on both of these medication for over 2 weeks now and it's not helping.  The codeine gets me drowsy when i am at work, but i am still coughing.  I barely sleep at night b/c my coughing would wake me up.  What type of doctor should I go to next.  I have Never had this problem before.  thanks for the help

truong

[National Jewish]

You should see a lung specialist, also called a pulmonologist.  It would be preferable to see one with a special interest in unexplained cough.  It may be possible to explain the reason for your cough with testing.  You should at least have a chest x-ray.  Additional testing would depend upon your age, smoking history and whether or not you have heartburn.

[DrNad]

It is indeed very astonishing that you have cough for almost three months now and you don't have any chest x-ray.

[nurse12hr]

Could be undiagnosed asthma.  My asthma is typically manifested by severe bouts of frequent coughing.  Went undiagnosed for about a year, just "post nasal drip" or "allergies".  See a pulmonologist ASAP.  A simple inhaler has changed my life!

[nurse12hr]

Here, I found something...

"1.1.2 Do all asthmatics wheeze?
No, not all asthmatics wheeze. Although wheezing is extremely common in asthmatics, in All About Asthma, Dr. Paul says, "It is important to note that not all asthmatic symptoms need be present for one to experience an asthma attack. For instance, not all asthmatics wheeze. And sometimes wheezing is so slight, it can only be heard with a stethoscope. With some asthmatics, coughing is the only symptom present." Similarly, in Children with Asthma, Dr. Plaut states that children with chronic coughs "may have asthma even though no wheezing is present." He diagnoses such children with asthma if their peak flow improves when given an inhaled bronchodilator.
1.1.3 What is "coughing asthma"?
In Children with Asthma, Dr. Plaut defines "coughing asthma" as "a form of asthma in which coughing is the only symptom and there is no abnormality in any lung function test." This condition is also known as "cough variant asthma." Coughing asthma often improves when standard asthma medications are taken. "