Why does back shoulder blade pain occur?

There are times when I struggle with the occasional pain in my shoulder blade.

It does. It's actually kind of bothering me. I get massages, but it only works for a moment, and they come back after a while.

I wonder in many ways if it was caused by poor posture

I'm getting curious. Does anyone know anything about back and shoulder blade pain? Please let me know if you are knowledgeable about it.