Were you by any chance the "high-functioning" member of a dysfunctional family growing up? One of the hallmarks of dysfunctional families is that they don't allow family members the space to act outside their designated role, so the high-functioning one can never fall apart (b/c if they do, everyone else falls apart).

Everything you've written in this thread is exactly how I feel. And now my brain or body or something won't allow me to ignore it anymore, and my life circumstances no longer allow for my habitual ways of coping, so I feel like I'm going crazy and out of control. The people around me won't let me "not function", and my-self won't let me "function", so I'm just in free-fall.