I got a saddle pe at the end of nov. 2020 due to right hip replacement surgery. doc removed multiple clots but not all of them. i've been on eliquis ever since & just had a d-dimer come back at 633. the range is 500 ng/ml feu. what could this mean?

It could mean the old clot(s) may still be persisted. Eliquis only prevents the new clot and your body dissolves the old clot(s) which is called fibrinolysis. High D-dimer means the fibrinolytic process may be present; however, your D-dimer is only borderline high. You have provoked DVT but with severe PE so the decision to stop blood thinner will be tough, D-dimer level alone is irrelevant.