I strongly recommend that you go to see your primary care doctor
about this issue as soon as possible. These symptoms sound quite serious, and it is important to get to the bottom of the potential causes. When you go to see your doctor, make sure to let them know how this pain and numbness
came on. In particular, it is important to know whether this came on suddenly as a result of an identifiable injury
or whether it has been developing gradually over time, as this will help narrow down the list of potential causes.
Pain and numbness together usually indicates some sort of nerve inflammation or compression. Typically there are two nerves in the arm that are commonly injured. The first of these, the median nerve, gives rise to carpal tunnel syndrome, where the pain and numbness is mostly on the thumb side of the hand. The second of these, the ulnar nerve, typically gives rise to pain and numbness which is more on the pinky side of the hand.
Based on what your doctor discovers, they can recommend various treatments, including potentially anti inflammatory medications, supportive splints, rest from vigorous activity, physical therapy, or in more severe cases referral to an orthopedic specialist.