Hello, I m sorry to hear you ve been struggling with this cough for 2 months. Another common cause of coughing is reflux or heartburn. Symptoms of this include experience a burning pain in the middle of the chest, sour taste in the mouth, and coughing especially when lying down flat. You could try an over the counter acid-suppressant like ranitidine or omeprazole. Some people find benefit from using a wedge pillow or elevating the head of their bed to reduce reflux of stomach acid into the airway. Asthma is also a common cause of cough that can be triggered by cold weather. Asthma may not cause any abnormalities on routine pulmonary function tests (breathing tests). A methacholine challenge test (or bronchoprovocative testing) is another test that may be more likely to diagnose asthma if your symptoms are caused by it. Asthma is treated with various inhalers depending on the severity of your symptoms. I hope you feel better soon.