you wrote that your chiropractor/sensei would stretch your spine "so that discs can slot back in".
I sure hope those are your words, not his, otherwise my advice would be never to let him come anyplace near your neck ever again!
With a martial artist who speaks of "discs slotting back in" I have no problem, but with a chiropractor it's a totally different matter.
This is probably a needless post, as I am sure the phrasing was your own, but I will post it anyway, just in case!
I wish you a lot of interesting hours in the dojo this year,