History of DVT w/vinecava filter tightness above knee w/swelling in calf and ankle itching behind the knee and aching on lovenox (enoxaparin) 120 sub Q2x day new clot?

Ultrasound. On Lovenox (enoxaparin) it would be unlikely to develop another blood clot, however if you have a hypercooagulable condition there is some risk for excess clotting. Have an evaluation with your doctor and you may need an ultrasound to look for progression of the clot.
Possible. Unfortunately, though rare, you can still develop a clot even on medication. The filter doesn't prevent clot it just prevents it from shooting up to the lung.
Likely. The vena cava filter will nöt prevent clot DVT but will decrease embolism to the lungs. The Lovenox (enoxaparin) should reduce your risk DVT . Based on your history it appears you have a hypercoagulable condition. This may be due to some factor like apac, c, s deficiency or malignancy. See a doctor as thrombophlbitis should be considered.
New clot is possible. Although you are anticoagulated with lovenox, (enoxaparin) it is still possible to have a another clot. The fact that you have a ivc filter should protect you from developing a pulmonary embolism. You may need to switch your anticoagulation agent to another low molecular weight Heparin or xarelto or warfarin.