It is to be considered after 2 months of useless thorough assessment & investigations. Approaches:  To examine for eosinophils (blood and sputum) and if the tests are positive, we may consider inhalational steroids. To examine for GERD and if the results are positive,  we may consider anti-reflux measures.

In case of 1 & 2 negative results, we may consider Gabapentin  (to start with 100 mg/day and to increase the dose day by day till response and to  a maximum of 1800 mg/day). Please share your opinion.