I was diagnosed with complex PTSD 2 years ago, it makes sense to me now delving back into my childhood living with a neurological disability plus the pre verbal and adolescent trauma I experienced.
I believe many people do not realize they have complex PTSD from their childhood. Social anxiety is a symptom of my traumatic neglectful childhood, so it maybe a similar case for some people on here who have experienced trauma, neglect or abandonment when they were younger, no matter how mild or severe. We all react to traumatic and stressful situations in so many ways that can set the foundations of developing mental health difficulties if not addressed and treated early on in life.
Edit - This is an interesting Youtube channel about Complex PTSD - CPTSD & AVOIDANCE: Do You Struggle in GROUPS? (Resilience Series)
https://www.youtube.com/watch?v=2bSqxUvoVnk
Edit - Just like to add, dissociation (spacing out, disconnecting etc) is a common theme for people with PTSD. I do it often, I may pace around, stuck in a cycle of rumination about certain events that happened to me in my past or I sit and stare at an object for a few minutes feeling numb.