hi, thanks for providing the brief history of you. Since you mentioned you had mucus drainage in November and you were on antibiotics and steroids that means you had some sort of infection. Even you are not a smoker. Why don t you just get your sputum culture get examined once in lab. It is safer to get this done as this mucus is not going away on its own. Also check your pulmonary function test, which can help assess the functioning of the lungs and the capacity of it. Also you can take one chest x-ray if any accumulation of fluid is there since you mentioned the posterior aspect of the lungs. Also in the mean time you can start doing breathing exercises and steam inhalation. Which help strengthening the lung tissue and muscles also steam will help keep the lungs humidified. Avoid taking any cold food and also keep your lungs area covered. Keep the cotton in the ears to avoid any cold air to pass in by. Breathing exercises - there are types of it, i will mention here which you can perform by your own or can take a guidance from a physical therapist, it might take a day or two to learn and later you can follow at home every day till we do a reassessment of your lungs via pulmonary function test. 1. Deep breathing 2. abdominal breathing 3. coastal breathing 4. pulsed lip 5. diaphragmatic Also perform some slow and simple CR endurance training like shoulder girdle movements, core strengthening, cycling, etc DO NOT PERFORM TREADMILL TRAINING. For pain as you mentioned it is happening in your back from shoulder blade to ribs, you can use hot water fermentation for it. For more queries you can ask me a direct question. With the grace of God i wish you a speedy recovery. Regards Jay Indravadan Patel