elbow grinding, locking, cracking after Tommy John surgery

Had Tommy John and arthroscopic surgery a little over 2 weeks ago. Had the problem of my elbow constantly needing to be cracked or it becomes painful. To crack it I flex my arm and straighten quickly and do this a few times, giving me temporary relief for maybe half an hour. I've been doing rehab every day as instructed and wearing an arm brace. My physical therapist says it is probably due to joint swelling and my surgeon didn't think much of the problem. Also, the crack is sometimes painful and the surgery was due to a ligament that became stretched over time, not torn. Should I be worried about this? Anybody else have an idea of what might be wrong?