她摔了一跤，眼睛上方起了一个包，挺疼的。

The fall left her with a painful swelling above her eye.

《牛津词典》

医生给了他一些治胃疼的药。

The doctor gave him some medicine for his stomachache.

youdao

“我告诉你，会有点疼的。”她警告他。

"I daresay it will hurt a little," she warned him.

youdao

It's when I'm weary of considerations And life is too much like a pathless wood ; Where your face burns and tickles with the cobwebs broken across it, and one eye is weeping from a twig's having lashed across it open.

那是每逢我厌倦于操心世事,而人生太像一片没有小径的森林,在里面摸索，一头撞在蛛网上，只感到验上又热辣，又痒痒，忽然，一根嫩枝迎面打来,那一只给打中了的眼睛疼得直掉泪。

耶鲁公开课 - 现代诗歌课程节选

Or maybe during the meal, you are feeling a stomachache

又或者在吃饭的时候，你觉得有点肚子疼。

I will 课堂 - SpeakingMax英语口语达人

So, if somebody pokes you with a stick and you say, "Ouch," because it hurts, the poking and the "Ouch" is an unconditioned stimulus causing an unconditioned response.

如果有人用棍子戳你，你会因为疼而叫出来，戳的动作和你的喊叫“,这就是无条件刺激引起了无条件反射。

耶鲁公开课 - 心理学导论课程节选