Hi. Thanks for your question.
I am a board certified neurologist in the U.S. I will be happy to help.
Numbness in the hand can be due to a variety of different problems. If the symptom is only numbness, with no other neurological symptoms like slurred speech, weakness, balance problems, etc..., then there are 2 main possibilities to consider.
The first would be a compression of the nerve in the arm or the wrist, such as carpal tunnel syndrome (CTS) which can produce numbness in the thumb, index finger, middle finger, and half of the ring finger. This condition can also involve the palm. CTS would be a very common cause for hand numbness, often caused by repetitive types of activities over many years, but in other cases it can arise for no apparent reason.
The second most common cause would be a compression of a nerve exiting the spinal cord in the neck. This would often be accompanied by neck pain, but not always.
To evaluate this further, certainly a more complete history and an exam would be needed, and testing also may include a nerve conduction study which can help evaluate for the nerve function in the hand. You may consider seeing a neurologist this week if possible to help evaluate your symptoms. I would suggest seeing some physician for sure this week to make sure a full exam and history are completed and proper management can be determined.