Eugene:
If I'm not in danger and I'm on the right track, I would really like to keep going. I want the endless mind-ache to stop. More importantly I really believed from Daniel's book that I could do it, his no-BS approach really resonated with me, I still believe, I believe more after this highly physical experience.
I guess it's probably not strictly speaking necessary, but some help diagnosing would be good. At least an assurance that I'm not in medical danger?... Should I stop meditating until I find a teacher? What happened?
Thank you for reading this mess.
Not a mess at all. I think many of us know the kind of experience that you are talking about.
The interesting thing is there seems to be a bit of beginner's luck a lot of the time... People can have quick experience when they start sitting, almost like a sneak preview, and then it takes a while to work back to that cutting edge. So don't be surprised if the next time you sit it doesn't go the same way. Pretty much the whole path of practice is sitting, glimpse of something, losing the something, sitting for a long time and getting frustrated, but then (usually when you give up on making progress) the something comes back and more, then it's lost, then you work up to it again, etc. etc.
So, here's the thing: seems like you are primed for this kind of work in one sense, but also maybe a little fragile in another sense. The whole trick of getting out of being a dark night yogi is to learn to sit gently, without pushing progress, but also to sit daily, without taking the momentum away. A dark night yogi tends to be prone to sitting too long or seeking too strong and experience, which only re-traumatizes their psyche. There is a tendency to say "I'll take all this abuse if it will fix me", but this is NOT a [EDIT:] healthy approach to meditation practice.
What you did was perfect. Explore, investigate... but when it becomes a little too much, STOP and let it calm down and re-integrate.
Now all that said, yes the A&P is probably going to be exactly like what you experienced, lots of vibrations and a feeling like you are being shook/scattered apart. It can be overwhelming if you don't have a good foundation to ride it out without freaking out. It's also really wild and amazing, too. Kinda like an insane roller coaster or a rocket ship rumbling through the turbulant atmosphere into space. It can also feel like having an anxiety attack. If you can ride out the sensations of an anxiety attack, it comes and goes, but if you start freaking out, it can basically become an anxiety attack.
It is HIGHLY recommended that you develop your support team before getting into disruptive stuff. Finding a local practice group and teacher is best. Posting on here is okay, but it's kind of a crap shoot on who is around to reply. Some people set up practice logs here, on AwakeNetwork (my personal favorite place for people with committed daily practices), or Reddit Stream Entry, etc. Many of us have worked with meditation teachers/fellow practioners via skype/google hangouts and that has worked well, too.
You have been given a nice sneak preview -- how very kind of the universe!

But now take precautions and set up things so you can do this practice and make progress without really disrupting your life.
Hope this helps, best wishes!