Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
Let me say this from having looked up many things as a patient advocate: Having some familiarity with terms and conditions is valuable to help you talk with your doctor and formulate the kind of questions that get informative answers. Remember that it never substitutes for the information from your doctor, who is the only one who is qualified to interpret your particular medical testing.
There are many things, for instance, that one can read online or in a medical report that sound ominous in general but that can be very benign (harmless) in your particular case.
One thing you can rest assured of: if it was truly horrible and required immediate attention, you would have been told about it right away. I hope that helps set your mind at some ease.