Summarize:

If your legs are swollen or you have been sitting for a long time as in a overseas plane ride, blood clots can form and spread to your lung arteries, causing blockage. Lung conditions cause chest pain that can worsen when you breathe, move, or cough.  Get to an emergency room as quickly as possible. Lung conditions may require emergency surgery to alleviate symptoms. Pneumonia is an infection that affects the air sacs in the lungs. They become inflamed, and can fill with fluid, which results in the phlegm and mucus you see when you cough. The chest pain you experience may be accompanied by:  Fever Coughing up mucus or phlegm Fatigue Nausea, and vomiting In mild cases, you can simply rest at home and wait for your immune system to fight off the infection. But if the infection grows severe it can become life-threatening, especially in children and the elderly. See your doctor if:  You have trouble breathing The chest pain worsens significantly You have a fever of 102 F (39 C) or higher that won't go down Your coughing won't subside, especially if you're coughing up pus Be especially careful with children under two, adults over 65, and anyone else with a compromised immune system. If a bacterial infection has caused the pneumonia, the doctor can prescribe antibiotics (azithromycin, clarithromycin, or erythromycin) to fight the infection and speed up recovery. However, even if antibiotic treatment is not an option for your infection, he can still give you medication to deal with the chest pain or reduce the coughing that worsens the pain. A pulmonary embolism occurs when a blockage develops in a lung (pulmonary) artery. Pneumothorax (collapsed lung) occurs when air leaks into the space between your lungs and your chest wall. Both conditions cause severe shortness of breath or a bluish discoloration of the fingers and mouth. In delicate patients such as the elderly or long-term asthma sufferers, the intense coughing from pneumonia can sometimes cause a lung blockage or tear in the lung. If you suspect a pulmonary embolism or pneumothorax, then seek immediate medical attention. In addition to chest pain, both conditions cause severe shortness of breath or a bluish discoloration of the fingers and mouth. Both conditions require immediate medical attention. The blood leaking into the chest cavity or the air escaping into it can rapidly collect and compress your lungs. These conditions will not resolve on their own, but require medical assistance. Call emergency services or get to an emergency room as quickly as possible.
Recognize the severity of lung conditions. Look for the symptoms of pneumonia. See a doctor if your pneumonia symptoms grow severe. Ask your doctor for medication. Watch for the symptoms of pulmonary embolism and pneumothorax. Seek immediate medical attention for pulmonary embolism and pneumothorax.