Hey, sorry some other questions of yours didn't get responses. I forget about this forum sometimes! Yes! I've had this. Not routinely though. Are you having this symptom all the time. I was a long time GERD sufferer and have had other digestive issues with constipation, diarrhea, intermittently. So, I get it. It's all a big pain. The pain in the middle of my back can be maddening. I also had gallbladder issues. So, for me, the solution was actually weight loss and diet changes. I dropped 10 pounds and eventually a bit more and it almost completely solved my GERD. And diet took care of the rest. Before that, what worked for me wasn't PPI's, hated those. I took simple Pepcid or Tagamet. Worked well and then things like watching acid, cutting down on sugar and fatty foods made a huge difference.
Here is an interesting link to an old post here at medhelp and I'm sure there are many many others of people who have the same issues as you (and me) https://www.medhelp.org/posts/Digestive-Disorders---Gastroenterology/Back-Pain-associated-with-GERD/show/233552.
Here is something backing up that this type of mid back pain can be caused by acid in the esophagus. https://www.merckmanuals.com/home/digestive-disorders/symptoms-of-digestive-disorders/chest-or-back-pain . It does also mention the other reason could be heart related but with your history, it would make sense that it is all GI related. Have you had a physical recently though to make sure?