47 yo M has 6 month hx cough w/frequent episodes of paroxysmal coughing spells making it difficult to converse w/others. Small amts white sputum, no hemoptysis. Wheezing & Chest tightness too. Works as industrial welder after losing automechanic job abt 11 months ago. Lived w/wife in same house for past 20 yrs and recently traveled to Maine 2 months ago during which he felt well. Abd is protuberant. Office spirometry is normal, CXR normal. Management?
a) Bronchodilators and corticosteroids
b) Smoking cessation counseling
c) Environmental allergen avoidance
d) Surgical lung biopsy