@amyjo4003 I'm sorry for your difficulties. I had cervical spine surgery at Mayo Rochester. I have been through lots of physical therapy and I also have thoracic outlet syndrome that causes tight muscles and tight fascia that pulls from my neck and jaw through my chest and to my pelvis. I have had my pelvis shift out of alignment because if this, and it can easily shift and twist which does cause sciatic leg pain. My physical therapist has taught me things to do to realign it and that stops it. The more I work on my core strength which I do by riding my horse, the better my back and neck feels and my pelvis stays in better alignment. I just walk on my horse. The barn owner who is also a friend was injured on her horse, and she has an artificial disc in her lumbar spine and rides her horse a lot with no problems. The symptoms I feel when my pelvis shifts is the same as you describe, a pain on one side of my low back that also goes down my leg. I can get an inflare where one side aims toward my belly or it can twist up or down. This causes the muscles that connect the spine and pelvis to get tight, and sitting a lot also helps shorten some of the muscles. The link below explains how the pelvis alignment can mimic pain from a lumbar spine problem. What I would suggest as a first step would be to see a good physical therapist for an evaluation and I would recommend one who is an expert in myofascial release because they know how to release the tight fascial webbing and surgical scar tissue that is binding everything together. There is lots of detailed information in our MFR discussion about this.

Has a doctor helped you with your balance and evaluated the reasons for this? A PT can probably help that too. If you do want to go to Mayo for an opinion on your spine, I would highly recommend my neurosurgeon, Dr. Jeremy Fogelson. I had a great recovery from spinal cord compression in my neck with his surgery.

Here are a few links that might be of interest including my patient story and our Connect discussion on myofascial release therapy where you can find information and a link to find providers at https://myofascialrelease.com/find-a-therapist/. I hope you will share your experience and how you are doing as you explore further care. I'd be happy to answer questions. Be well.
https://trainingandrehabilitation.com/identify-treat-lumbar-plexus-compression-syndrome-lpcs/
https://connect.mayoclinic.org/discussion/myofascial-release-therapy-mfr-for-treating-compression-and-pain/
My Mayo patient story
https://sharing.mayoclinic.org/2019/01/09/using-the-art-of-medicine-to-overcome-fear-of-surgery/