Sorry. How I describe it to other people is usually that "I can't talk or think, even in my own head" "I have no thoughts" "It's kind of like I'm stuck in a different personality, only it's like I'm just a much dumber version of myself"
I also get confused a lot and have a really hard time making things sound coherent
How I know I should, and can be talking hasn't changed, and when I'm like this, I hate all my thoughts. I can't stand listening to how boring and dull I sound. I'm CONSTANTLY internally (and sometimes when externally) telling myself to shut up. I hate how I sound, so I'm always apologizing.
Social things involving higher levels of cognition (Spontaneous/self-generated thoughts, telling jokes, being witty, etc.) are impossible for me when I'm like this, but I used to never have any problems with any of these things. This never changes under any outside circumstances