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.
Considering you just travelled I would ask about checking for any infections you could of been exposed to during your travel?
Taken from google search:
“An elevated D-dimer may be due to a VTE or DIC but it may also be due to a recent surgery, trauma, or infection. Elevated levels are also seen with liver disease, pregnancy, eclampsia, heart disease, and some cancers.“
Check back with your doctor on why your d dimer maybe elevated.