Hi
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Since it involves hands and back only possibility of pinched spinal neves should be looked into. The other possibility is Scalene Myofascial Pain Syndrome. When scalene muscle is the cause of pain, the pain is referred chest, inner lining of scapula, shoulder, posterior and lateral sides of the arm right up to the thumb and index finger. When this muscle shortens, this can press on brachial plexus and the subclavian artery and can compress or irritate these structures and cause symptoms such as abnormal sensation, cold extremity, claudication (spasms), and lymphedema in the involved extremity. Diabetes, low sodium, magnesium or calcium too could be the cause).
I think you should discuss these possibilities with your doctor. It is difficult to comment beyond this without examining. A comprehensive investigation is required keeping all the points in mind. Take care!
I have had this problem but it usually when I have been writing or typing too much. Since I type for a living, I experience this quite often. You might want to see your physician about this and see what kind of exercises you can do to stretch the tendons in your hand and strenghten the muscles. Hope I was able to help you.