Suggest Treatment For Chest Cough And Tiredness

Hello, In November after visiting gym I ve got stuffed and 100% plugged nose, later developed chest caugh, pain, tiredness, thought I might have had pneumonia.. Took a lot of rest, lung teas, herbal tinctures, veget. and fruit juices etc. Lung Xray was OK. 2 weeks of antibiotics didn t clear it up. Up to now having smelly yellowish mucus coming out of my Bronchi s. Much worse after any kind of small walk, excercise. I am very concerned, it feels like infection in my chest that is not going away. Dr. ordered spirometry and metacholine tests, that suggested mild Asthma. Recommended cortison puffers only. I gave sample of yellow mucus - came out as inflamation only. What should I do next? So far I stayed off work last 3 months, taking care of myself, it seems getting slowly better until I go for a little walk when symptoms come back big time. What other test should be done to find out the real cause? I feel, that if it is not cleared, it will be getting worse over time. I used to do a lot of sports here as well as in Europe since childhood, until 3.5 months ago, and I am very worried about the future of this medical issue. Thank You, Radka