Pleurisy is an inflammation of the membranes that line the chest wall and also cover the lungs. Symptoms include pain that occurs when you take a breath and worsens when you cough or breathe deeply. Sometimes, fluid accumulates around the lungs, which can lessen the pain, but as it builds up, it causes shortness of breath.
Pleurisy can result from a viral respiratory infection such as the flu or pneumonia, from lupus, rheumatoid arthritis or other autoimmune disorders, from tuberculosis, pancreatitis and occasionally from pulmonary embolism (a blood clot that travels to a lung, usually from a leg). Sometimes, pleurisy occurs with no identifiable cause, which seems to be the problem in your case. Doctors diagnose this condition by listening for a characteristic "friction rub" with a stethoscope. A chest x-ray can show whether you've got pneumonia, and blood tests can identify any infections.
Treatment for pleurisy depends on the underlying cause. For example, if you've got pneumonia, you'll probably be put on antibiotics. Nothing can be done for viral infections - they usually clear up without medication, although I would recommend trying the herb astragalus, which has antiviral activity.
Your doctor may recommend over-the-counter anti-inflammatory drugs to relieve the pain and, if you've got a cough, may prescribe a cough medicine containing codeine.
To prevent future episodes, I suggest taking astragalus long term. It is available in tablet and capsule forms. Take two tablets or capsules twice a day unless the package label directs otherwise. You can continue to take it indefinitely. I also recommend using an immune-enhancing mushroom formula. In addition, I suggest consulting an osteopath for manipulation to free up chest motion. You also might want to consult a practitioner of Chinese medicine.
Andrew Weil, M.D.