Hurts to pump

This is the second time this has happened where my left side feels bruised and is super sore from pumping. I feel like it’s from being over worked as my left only produces about half of what my right does, both not a lot anyway. I’ve been trying to power through the pain as much as I can so I don’t mess up the little supply I have.

Has anyone else had this problem where one whole side just hurts and it’s not from being full? Also any tips on helping bring up milk supply would be great