I am so sorry that you are suffering these awful side effects. Hysterectomy destroys the integrity of the spine, hips and rib cage because the ligaments that are cut are also the support structures for the torso. That causes the midsection to collapse, the belly to bulge and can eventually lead to hip, back and leg pain.
However, it sounds like your pain started pretty much immediately. It is possible that the abscess is to blame, at least in part. But surgical positioning (especially that used with the robot) can cause spine and nerve damage especially if you had a long surgery.
Have you had any x-rays or other imaging to try to determine the cause? Unfortunately, if you have nerve damage, that's difficult to diagnose.
I hope you can get some help and relief!