Oh gosh, yeah I have a story from the other month with my OH. Apologies as it’s a long one, and I gotta give some context 
Backstory - I sometimes lose consciousness when playing, it’s something I can do alone when I really want to, and can actually be really good for my brain, so I do it when I’ve been super stressed 1-2 times every 6 months.
It’s like a complete reset, no racing thoughts, just perfect silence in my head, and can help me sleep. It’s totally safe, and actually pretty normal for me to experience when playing solo. (I disclosed this to my OH, so they were informed that this is a thing)
Now for the actual incident…
Turns out my current OH can actually reset my brain pretty easy, and has figured out exactly how to do it
. It happened 4-5 times in the span of my 2 week visit (I’ve never slept better
), and one of those times, we were in doggy, it’d never happened in that position before.
So reset button accidently hit, cue windows shutdown noise. My head drops forward, and, as my OH reaches forward to try and catch my head, they end up pressing me into the bed, my head lower than usual, awkward angle, all in the span of a couple seconds.
There’s a little crunch sound, I immediately come to, sharp pain in my neck, tears in my eyes. Non-verbal safe-‘word’ on show, immediate stop, and aftercare kicks in.
(One thing about my OH as a dom, their aftercare is impeccable
)
Safe to say everything was off the table for a couple days, as I couldn’t move my neck too much or sit up without pain. And my OH went searching for something we could use to prevent a repeat of this in the future 
(The item they found to protect my neck was this one, so that’s one for testing when I visit next)