I’m going to cut a v long story short but offer a bit of background for context... three years ago, I had a mild traumatic brain injury and post concussion syndrome which gave me a dreadful mental breakdown.
I’m about 75% recovered - certainly not completely back to normal as I lost the ability to see things in my mind’s eye (aphantasia) - and I am not as sharp as I was before. I’m sure my symptoms fluctuate with anxiety/ stress / tiredness etc and I get awful moments of brain fog, feeling spaced out and having a weird sensation of too much ‘space’ in my head (if that makes any sense!).
I actually had this odd sensation the other night when lying in bed trying to sleep, and l I can compare it to was a sense of feeling like I had lost all my memories of my past etc and all that existed was my internal voice and the thoughts about my present situation in the here and now.
On other occasions, I have woken up and felt like I had literally lost all knowledge of everything I had ever learned, but oddly enough could walk, move and talk ok - I just couldn’t recall any facts about literally anything for a couple of minutes. Similar to had times when my thoughts feel like they have slowed down so much, they are like wading through treacle and I struggle to find myself being able to think much at all.
My GP said a lot of head injuries and post concussion can include amnesia type symptoms but I am convinced these are more than that - possibly when my neurons aren’t firing correctly in my hippocampus (or something equally scientific sounding but is only a layperson’s theory!) and that I may be looking at some kind of dementia in my later years. 
I’m sure I am being overly pessimistic about things and I know the brain can heal immensely after being injured but I can’t help feeling a lot of my on and off symptoms are indicative of something more serious that will only be revealed in time...
AIBU to worry about these things so much? Has anyone else ever had any symptoms like these and what did you find helped?
Sorry if this isn’t posted in the right place...