You were doing fine after your 2016 concussion, until the long sessions of gaming in recent years?
Your issues might stem from the head ,neck and arm positions during ipad, computer or phone use and not related to the 2016 concussion after all this time.
Concussions also often involve some sort of neck impact or strain/whiplash that can show up later

Consider getting a comprehensive evaluation from a skilled PT or quality chiropractor.
Upper body postures, trigger points or old injuries can be a factor.

Any new medications in this recent timeframe?