Scivillage.com Casual Discussion Science Forum

Maybe you're confusing pain with referred pain.

"The science is clear: the brain makes pain. Pain is 100% brain made, like everything else we perceive. Threat signals from “insulted” tissues are only one factor of many that the brain considers before creating an experience of pain. The brain often even over-protectively exaggerates pain, sometimes sounding alarms so persistently false that it can become a much bigger problem than whatever caused the alarm in the first place: “sensitization.”---
https://www.painscience.com/articles/pain-is-weird.php

That's called idiopathic pain....as in the doctors are idiots who can't figure out the cause.