D-dimer showed elevated, CT of lung showed no clot what else could this mean? I'm worried! What other test should I request to be done?

How high? No one knows where to put the cut-off for d-dimer. It's an inexpensive and radiation-free screen for pulmonary thromboembolus. When suspicious for pulmonary embolus, we set the "decision level" low, so that many people tested will be false-positives, as i take it you are. Hope you are feeling better; best wishes.