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.
One thing I'd do is to ask for a list of things they've tested you for. I had a few follow up appointments while on warfarin (and beyond) and it appears that they were not as thorough with trying to find a reason as they might have been.
Hope you get back to being normal :-)
Some clotting disorder tests aren't affected by warfarin, but some are. I'd question them if the only testing you've had done (or that they're planning to do) is while you're still taking the meds.
Otherwise, I'd suggest taking notes at the appointments and making a point to get copies of the lab results yourself. It's always good to have those things on file later.