Hello, You have been a smoker since 10 years. You have quit smoking since last 3 months. Presently, you have been coughing few times but you have been spitting white foamy sputum and you also have difficulty breathing. Body identifies smoke as an irritant and tries to prevent it from traveling down the airway this causes cough and excessive mucus in throat months after quitting smoking & goes away gradually. Smoke from vehicles and industries are act as irritants for the throat and rest of the airways. This causes increased mucus in throat. You can take steam inhalation, nasal sprays are also helpful. You can take cough syrups with mucolytics to get rid of the foamy mucus faster. For resistant cough you may need a course of oral antibiotics. You can take vitamin C tablets. Avoid taking food that may increase mucus products like curd, oily - spicy food, alcohol, smoking, avoid going outdoors that are heavily polluted with smoke, dust, etc. Take warm soups and broths to soothe the throat. Smoking can lead to chronic cough and wheezing. They experience symptoms of shortness of breath, wheezing and chest tightness. Accumulation of superfluous mucus in the lung airways reduces the lung functioning resulting in breathlessness. Smokers commonly stop deep breathing after quitting smoking thus that may also be a cause of difficulty in breathing. Do deep breathing and also breathing exercises. Medical conditions that cause difficulty in breathing are development of bronchitis, pneumonia, COPD, etc. Get clinically examined, get tests and imaging tests done. Get treated at the earliest. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician