multiple brain injuries
 

is it possible for a brain injury to lay 'quietly in the background' (like with little or no visible symptoms) for years and then with the next hit to the head, explode into something big???
[even if that next hit to the head isn't a 'super hard' hit]

Well yes, there is that possibility....Hitting your head can be cumulative, problem with saying out loud it gets taken wrong....Look at so many posts that a simple tap to the skull and some just freak out....There here all the time....

Hope you are seeking medical help!....Best wishes, and get well .