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It is very likely the diagnosis is right.
Generally X-ray chest and at times of para nasal sinuses
/ followed by Spirometry
(lung function test) are done at some stage. A battery of tests to evaluate allergy
is done at times.
Causes like tuberculosis
and cancer must have caused other serious problems to draw attention. That one is generally well otherwise and the long duration - goes with the diagnosis of Chronic Bronchitis
Wishing speedy recovery