Hi Charlie,
Don't worry I had this too. I used to cry when I was at the doc's or had to discuss the concussion with anyone, I couldn't help it, tears just were suddenly there! It was very odd, and it made me feel quite immature, but I know it wasn't my fault. I am not still a bit different emotionally I think, but I can discuss it without crying and overall have a much better control over my emotions even though I am still suffering from PCS, so I am sure you'll get there too.
With regard to feeling like you aren't sure who you are and who you were, can totally relate! I had these exact thoughts, it is very odd and very unpleasant. I found talking to friends who had known me for years helped. If I ever was having a moment of "who am I? was I always like this?!" they were there to reassure me that I had always been like that or whatever. I think with PCS you over think everything!
I really hope things get better for ya!
Rosie