Brief Answer:
Several possibilities.

Detailed Answer:
I read your question carefully and I understand your concern.

Judging from the symptoms you describe three main possibilities are to be discussed. First would be a blood circulation problem, a blockage in a blood vessel. However it would be associated by changes in color, local temperature, and non palpable pulse at the wrist.

The other possibility would be a peripheral nerve compression like carpal tunnel syndrome, or compression of a nerve root in the neck which may manifest with pain, numbness and weakness in the area supplied by the nerve.

Another common possibility would be a rheumatological condition like rheumatoid arthritis which may also produce such symptoms alone or by causing nerve compression by its turn. Usually in this case the symptoms are more pronounced in the morning, with stiffness.

It might have been possible to narrow the list of possibilities if you provided some more detail, such as whether the symptoms are on one or both hands, do they involve the arm/forearm/neck or the lower limb, is there any local change such as swelling, change in color, temperature of the skin, whether the pulse at the wrist is well detected, whether the pain and numbness include all fingers or only some of them, whether the symptoms are more pronounced at certain times of the day or triggered by other factors.

For now a physical exam is needed to check for local changes and according to the clinical suspicion some blood tests and nerve conduction studies might be needed.

I remain at your disposal for other question, possibly providing some of the information I mentioned.

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