Hello,
Thanks for the query to H.C.M. Forum.
I would come up with these possibilities for this type of
chronic cough, these includes.
1 .Allergic
bronchitis ( asthmatic ) , usually in this type of cough allergy is responsible .Diagnosis can be confirmed by physical as well clinical examination by a physician . Usually this type of cough is stimulated by mite, dust, cotton fiber, hay , cold , sudden rise & fall of temperature , pollen, mold.
Avoidance of these provides relies.
Sudden exercise increase demand of oxygen , but due to
bronchoconstriction there develops cough.
2
Throat infection is the next reason. Diagnosis can be confirmed by swab from the throat.
3
Eosinophilia may be possible next reason.Diagnosis can be confirmed by blood examination for eosinophils count.
In my opinion as all tests are normal so ,consult a physician and get his treatment for asthmatic allergic bronchitis.
Good luck.
DR. Het