You don't give the reasons behind the fusion, but I would assume you had an adolescent scoliosis, and it's good that you had thirty years with minimal trouble.
Firstly, I would have an assessment for a short leg, a common cause of scoliosis. It's a bit technical, but sometimes it should be the whole shoe insert, and sometimes just the heel. Just how many mm is also a bit of trial and error. In Chiropractic we use proprioceptive testing, slapping on your arms (with your eyes closed) to see how steady you are with different thicknesses.
Mostly what I'm concerned about is those "little spasms" in your leg. That needs careful neurological assessment for "long tract signs". It could be coming from the area of the fusion, or even your neck.
If the tingling is in all fingers, then you probably have a "thoracic outlet syndrome", usually caused by a fixated first rib, but sometimes a neck rib may be the cause.
If the tingling is in the thumb, index, middle (and sometimes ring finger) then we're looking at a carpal tunnel syndrome. If it's just in one or two fingers, then it's from your neck.
As you can see it's all quite technical, and what's needed is a careful and thorough Chiropractic examination, and perhaps an assessment from a neurologist about those little spasms.
Start with some erect (standing) X-rays of your whole spine and pelvis, Helen. Your whole back, stem to stern, is complaining and it needs to be managed in it's entirety.
I recommend you start looking for a careful conscientious chiropractor in your area. Ask friends and family, and even your family doctor.
I hope this has contributed.
Dr Barrie Lewis