Mark,
I'll ask for more details at some point and let everyone know. I agree that kind of desensitization training could be helpful, but it honestly sounds scary. In theory I get that small head bumps aren't that big of a deal, but my experience has suggested otherwise. I made a thread about the ceiling head bump noted in my signature over a year ago, asking about the significance of these, and you said (not calling you out here or anything, just trying to illustrate my experience) that it wasn't anything to worry about, but that bump preceded a major worsening, and I haven't felt as good as I did before that since then.

Another instance was falling while xc skiing. I didn't hit my head, and didn't really have that great a startle response because I was surrounded by kids I was coaching and didn't want to freak out in front of them. But, once I got home, I started to feel worse, which precipitated anxiety. It's usually an increase in symptoms that causes anxiety in my experience, not necessarily the other way around (although I get that these can be difficult to distinguish).

Further, I've had anxiety spikes unrelated to head stuff (relationship issues) that do cause an increase in symptoms, but only very temporarily, whereas head bumps of relative significance cause much longer lasting setbacks. So, it's hard for me to rationalize that it's just anxiety when other instances of just anxiety don't produce the same effect as a head bump + anxiety.

I get that this is really complicated and all kinds of other factors could be at play, but given my experience it's just really hard to fully believe that these head bumps aren't doing some kind of damage, whether to my brain or skull or nerves or whatever, that will result in a setback. I know I'd be better off without this belief, but part of me just simply thinks it's true, and I have a hard time shaking things that I think are true.