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ELI5: Why do ear infections hurt so much?

When people get middle/inner ear infections, it hurts a lot. Why is that? I get that fluid builds up in there, but why does that trigger a bunch of pain?
gpt
Usually ear infections involve the middle ear, which is the chamber between your ear drum and the little organs that allow you to perceive sound/body position. The only way out of that chamber is through the Eustachius canal which leads to your nose. When that chamber gets infected and the canal swells up and shuts (for example when you have a cold and some microbes travel up the canal into your your ear), fluid and pressure builds up inside. There are many nerve endings in and around the ear, most notably the facial nerves actually passes straight through that chamber. That’s why pain from an ear infection feels like it radiates so much through your face. The thumping sensation comes from your body natural response to trauma: inflammation. This means the blood flow to the affected area is increased and the tissues swell up a little, which increases the local pressure and makes you aware of the heartbeat in the area.