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 met with a consultant hematologist today who is an expert on anti coagulation. I asked the same question "can i clot again on rivaroxaban". The response was it is very very unlikely for people to clot again on rivaroxaban and will only happen in a very unlucky subset of people.
The pain could be residual PE recovery stuff. So many of us have had on going intermittent pain post diagnosis. It could be too that maybe you're getting a little worked up about the Xarelto stuff and so you're hyper focused on your body, feeling things more acutely than you normally would. With that said, pain in that area is often associated with gallbladder issues.
I think if the pain is concerning to you, consult your doctor.