What physically feels the worst?

If we're talking about unpleasant sensations, there's one I get that makes me feel nauseous that I can only describe as being like a smooth grooved surface with unwanted lumps in it and I'm travelling and lurching over it in some unseen dimension. (I've actually met at least one other person who described this without me mentioning it first, so it might be somewhat common. I have no idea.)

I was watching a Let's Play video of a video game the other day and the texture for the water's surface in-game somehow reminded me of it, and it made the video hard to watch.

If we're talking about actual pain, I've had food-related (possibly also medication-related) stomach pain that had me curled in a ball thinking I was going to die and then thinking that might not actually be such a bad idea because then the pain would stop.

I now assume that that must be similar to what some people go through with period cramps. No way I'd want to do that once a month. The handful of times it happened to me was more than enough.

Honourable mention: The weird sting and sensation that isn't actually a smell but is somehow in my nose if I accidentally touch a hidden juvenile thistle in a lawn. Those things are prickly monsters that are just a shade bluer than grass and you often don't see them until you've put your hand on one. Other sharp pains sometimes trigger that "smell" as well. I always associate it with the colour of those thistle leaves though.