Oh yes this is familiar to me. Mostly what has happened with me is that I'd get into the middle of a conversation & simply go blank. Suddenly there would seem to be nothing in my brain at all.
And I'd have to quickly regroup & try to figure out what we were talking about & what to say next. These episodes would invariably be accompanied by a surge of anxiety that I would have to stifle. I often would wonder if the person or persons I was talking to sensed something was going on with me (embarrassing!)
I've also had problems with racing thoughts in the past. I'd think of something to say in the midst of a conversation &, before I could say it, I'd already have thought of some reason why what I was going to say was wrong or not appropriate & I'd be trying to come up with a different response.
In the end, I'd often just end up saying nothing. I've always presumed these kinds of problems were related to anxiety.
I don't really have problems such as these anymore though since I seldom leave home.