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.
I had a DVT in my thigh with no swelling, heat, or redness (actually I didn't even have pain until the PE) so I know that even if you don't have all the symptoms you could still have a DVT.
Once again can you think of anything else that would explain the pain?
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Of course, if this is going to keep you from sleeping the rest of your trip, it might be worth stopping by an ER to get checked out.