I think you might get a lot out of reading In an Unspoken Voice by Peter Levine. It's like Trauma-Sensitive Mindfulness how past trauma and stress can cause both emotional/physical pain in the present while also making us more prone to shutting down or lashing out in response to others.
Glad it's helpful! I've been reading this book on somatic experiencing and finding it also very explanatory. Best of luck and take care!
I've started experiencing this occasionally over the last year after doing a deep dive into meditation. At first it was in the context of a specific meditative state that was transient and predictable. But I recently started noticing it kicking in in other situations, especially those involving conflict, anxiety, anger, etc.
The first thing that I've found really useful is to read up on the neurological underpinnings of trauma. The first few chapters of In An Unspoken Voice by Peter Levine are very good at laying out what happens when traumatic associations get triggered. There's also a Wikipedia article on polyvagal theory that lays out some of it, or you can google "polyvagal theory" or "polyvagal trauma", or read up on the sympathetic and parasympathetic nervous systems.
There are two basic responses -- the classic "fight or flight" response and the "freeze response". In both cases, a traumatic stimulus actually shuts down normal brain functioning. This is particularly pronounced for the freeze response, which I'm guessing is what's going on for you, for u/JulesFiasco , for u/cae_jones , and for the author of that blog post. So it's in fact completely normal under some circumstances for an action that you can normally perform to just stop being available.
The second thing that helped after reading that was to start trying to remind myself that my emotional reactions around all of this was normal and typical of the situation. It's normal to be afraid or ashamed of shutting down/being unable to do something, it's normal to feel afraid/trapped/stuck when it happens, it's normal to be afraid or ashamed of coming out of shutting down into being angry, etc. The book by Peter Levine is really great for this too.
The third thing that helped was to find a therapist that specializes in working gently with trauma. The two main therapy types that are supposed to be helpful are EMDR and somatic experiencing. This is a website to help find somatic experiencing therapists near you. I've only had one session so far, but it's a very nonconfrontational method -- they're very deliberate about tone of voice, personal space, and eye contact to try to keep stuff non-threatening. The approach is more geared to producing a physical feeling of safety and regulation than at digging into the substance of traumatic memories/associations.
The fourth thing that's been helpful is to try to be socially engaged as much as I'm comfortable. Feeling that you're safe and welcome with other people is very soothing, even if they have no idea what you're going through. Online communities like this can also be good, and we all want to hear about how you're doing.
The fifth thing that's helped is exercise, especially when the fight or flight stuff kicks in. Just running, moving, etc. is really great to see that I can move safely through the full cycle.
I've got some other meditation-related stuff that helps when in the "just can't do X" phase that I'd be happy to share, but I think that it would come across as "just do Z instead of X, where Z is both weirder- and harder-seeming than X" unless you've got a lot of prior meditation experience. And I wouldn't recommend starting a meditation practice right away, for the reasons described in this book.
I hope this helps and wish you all the best.