For many minor concerns or symptoms of the respiratory system, you’ll receive care from your primary care physician (PCP). Your PCP will usually refer you to a pulmonologist if you’re experiencing the following:a cough that regularly produces blood or mucusa persistent or worsening coughdifficulty breathingunexplained weight lossDepending on the severity of your symptoms, a pulmonologist may refer you to a pulmonary surgeon who specializes in treating your condition.