Hello lark265: The Skeezyks has some sense of what you describe. For many years I've had this feeling as though there is some terrible "something" deep within the core of my being... sort-of a malevolent presence that, if it ever got lose, could do incredible damage.
Fortunately, it never has gotten loose.
I also have no formal diagnosis. I presume there are things written down somewhere for insurance purposes. However, they would be based on nothing since I've never had any kind of testing. I also used to think, if I could just get a formal diagnosis, it would help. I don't know. But at this point I've just given up thinking about it. I'm an older person &, for me, it's just too late to make it worth worrying about any longer. Good luck, though, with your efforts to get yours.