That's hard to answer without knowing more information..
Most likely not brain damage related..
It could be unrelated arm pain due to activities.
If you can list out your activities and symptoms it might help..

*There is often a whiplash effect with concussions, or some upper C spine misalignment strain..*
It can be a factor in arm pain, also repetitive motion (phone/computer/desk work, weight lifting.. etc)
many posts on upper cervical adjustment to search for.. or nucca , upper C spine..

PT evaluation (expert) could be explored, it might be just soft tissue related.