hi. I suggest that you write about it. As you did here But you can also write about it in a journal or on a piece of paper. Keep noticing it. I think as you do that, you will find more specifics which you can then tell your pdoc. It sounds like a horrible feeling. And yes I have had feelings similar to that. I can understand why you would feel like no one understands you. But I do think that as you can understand it more yourself, you will be able to explain it more. That's why I did suggest journaling or writing about it.
For me it might be some old stuff coming up. Stuff maybe I felt long ago. Sometimes when this stuff comes up for healing I feel it. And it is horrible. It makes me feel horrible. And there are feelings I had then that come up again. But I do not recognize them as feelings I had then. eg I feel so scared. ( the feeling I had then that was associated with what is coming up). Or I feel like no one can help. Another thought that might be associated with the body feelings that come up.
Sometimes I can say things that fit for someone. Other times I am off the mark. So I just offer this. Not knowing if it is in any way applicable to your circumstance