I took a pretty bad dog bite to the face in '88.
That didn't hurt at the time, and the first round of stitchery was ok (had to have scarring removed in a later surgery).
But the "swelled head" I woke up with the morning after was not to be believed. My head was twice it's size, green and purple, and would put a world of hurt on me if I tilted it even 1% of a degree.
PLUS- I had to give a days orientation to a new class of vet techs- I was the Director of the school, a full class was scheduled and no one else had a clue what I did on opening day.
So picture a classroom full of wide eyed newbies just waiting to get into the "animal game" and then a Franken'headed Director walks in and says "don't be alarmed- they very rarely bite you!!"
Yeah right.
I'd have to say back or neck pain is the worst in the way of stabbing, heartstopping pain. For the dull throbbing type I'd say a bad tooth.
My childbirth experience was a breeze.
I sort of take a perverse interest in pain and the range of tolerances that different cultures and people exhibit. When I am in pain myself I try to go with it, get the full sensation of what my body is trying to say to me, then tell my brain to turn off those receptors.
It's a field that needs much study.