I could be wrong, but it sounds more like CTS than a Cervical Spine problem. CTS can present bilaterally, and if that is the problem it's a lot easier fix. Also, you might want to try a splint, they help and you can pick them up anywhere.
I assume your seeing a specialist for your back pain, have mentioned to them the problems you're having with your arms and hands? It be interesting to hear what they think. I going to post a list of CTS symptoms below, Take Care
Symptoms of carpal tunnel syndrome
Numbness or tingling in your hand and fingers, especially the thumb, index and middle fingers.
Pain in your wrist, palm or forearm.
More numbness or pain at night than during the day. The pain may be so bad it wakes you up. You may shake or rub your hand to get relief.
Pain that increases when you use your hand or wrist more.
Trouble gripping objects, such as a doorknob or the steering wheel of a car.
Weakness in your thumb.
No, no real pain in my shoulder, chest, or neck area. The pain I experience is in my lumbar/mid back area. I do have leg, butt, and foot pain with numbness and weakness. The arm thing literally just came on all of a sudden one night. That I found strange because I really haven't been using my arms much for anything.
The pain in my arms is under my forearm, and goes into my wrist and hands. Worse on my right side. It really seems to affect all of my fingers, but the first 4 are the worst/numbest.
Personally, I doubt very seriously if your arm and hand symptoms are coming from your problem at T12, it’s just too low. Disc herniations in the upper thoracic spine can cause symptoms in arms, while problems in the middle tend to radiate into the chest and abdomen. The level you’re referring to can have symptoms similar to the mid-thoracic but generally causes pain in the groin or lower limbs and no motor deficit is usually noted.
I think your problems are more than likely related to CTS if your lucky or your lower cervical spine, I have a lot of problems in that area myself.
You have no neck or shoulder pain correct? Is this one arm or both, which specific fingers are you having problems with?
Your arms/hand symptoms could absolutely be starting from T12, even if it's referent pain. Have you tried aqua therapy? The warm water is relaxing and the pressure is off your spine and discs. Aqua therapy is very often available at a physical therapist's office. Your doctor should know where to get it. Good luck and many blessings!