HI, thanks for using healthcare magic
There are 3 common cause for a persistent cough. They are : (1)post nasal drip
associated with sinus disease. This is the most common.
(2) gastroesophageal reflux disease
(3) cough associated with asthma
With a previous history of sinus disease, you may want to consider the use of a topical steroid nasal spray
and an antihistamine.
If there are any reflux symptoms, you should treat these as well.
I hope this helps