What to do for this possible nerve damage in my arm?

It depends: First the nature of the nerve damage needs to be determined. Is it an entrapment syndrome with physical pinching on nerve, is it metabolic such as in diabetes or is there other causes? Once the nature of the nerve damage is determined then the proper therapy can be started. This may include medications, physical therapy or other modalities.

Evaluation: Before treatment can be discussed a cause needs to be identified. See a neurologist.