I don't know what to think about this. Are the doctors telling him that he is "healthy" and free to go all out but he is simply unable to trust his body (and his mind). Or is he having recurring symptoms that the doctors recognize as concussion-related but not endangering his health?
I suppose that there is a chance that repeated "good" days in practice will alleviate his fears enough so that he can still function as a major league ballplayer but that seems a longshot. I wish him all the best. At this point, it seems like he is fighting a battle on two fronts -- his actual concussion symptoms and what he perceives as concussion symptoms. While I don't think that is unusual, it does sound as though the latter may be Justin's biggest enemy.