I'm having recurring cold for almost a month now.. I also have persistent cough. I have some phlegm build up which I can feel when I cough and breathe.. Sometimes the breathing becomes difficult with a sound of phlegm getting pulled. Sometimes a kind of whistling sound also comes. I feel tired and out of breath with some irritability during this feeling. What can this be? Is this the start of asthma or some medical issues.. Should I consult a doctor?