i get that exact feeling all the time. it's really weird and you described it exactly on point. when i go through it i feel like nobody would understand, but i'm glad to know there are people who experience it EXACTLY like i do. I think it is some sort of derealization?
I'm also with you there on the bad focusing skills, listening to direction skills, social skills, paranoia,anxiety, as well as getting anxious in crowds and the really bad self esteem thing. It's partially the reason i joined PC.
never thought of puberty as avlady suggested, but that could easily be a factor.
hope this helped at all?