Memory of pain

So I'm wondering about the memory of pain. Talking with a little fellow tonight we said something about the body remembers the body stores perhaps events and I'm thinking as those events in our lives get processed and placed there are points in our body that reflect those events. Why does my knee hurt? There's something there in the past that produces that pain. Something to work through something to learn from something to reprocess something that has reoccurred. And so what is the connection of that pain to who I am today. And why does it hurt? I became aware of a pain in my shoulder a few years ago. I went and released that pain and let It Go. I'm wondering how to release this pain today?