stoppers. i am sorry you are having this. i am no diagnostician, but that sounds like dissociation, as the others have said.
i echo what the others have said, particularly strm, in asking your t about trauma, ptsd type experience. perhaps she knows what you are saying but doesn't want to alarm you with a name. i think, people with trauma and ptsd are most likely to dissociate.
some things i have tried to notice when i do this, is, identifying what may have triggered this? sometimes that can be a word someone says, a feeling that comes over me (like someone is humiliating me, or shame, or guilt). generally anxiety is the first symptom i notice. shame and guilt are big sensors and triggers for me.
this is a defense mechanism your body does to 'protect' yourself from discomfort, generally psychological discomfort, anxiety.
too. steady breathing when triggered, and putting your mind on something tangible. clapping (sounds silly i know), but that can keep me grounded. or tapping a song out with your toes if in a crowd. something about the physical movement and the sound helps me. even singing happy birthday to yourself.
you do need to have someone work with you on this, as, i know how scary it is. i have found myself places where i didn't remember driving there. or, whole conversations in a group where i am glazed over. it is scary. but, if it helps, alot of us here do this, so let us help you if we can!! jill