I also am having back pain directly after eating any food, in addition to back pain when I am pretty much abstaining for almost a whole day. The pain is unusual as it's not from a sprain or injury, and radiates all across the upper back around my waist. On some nights, my back pain is worse. I have, no whole life been a very healthy person. In 1974 I was rendered unconscious and jaundiced, doctors had thought it was acid reflux and prescribed antacids - for weeks. I was found on the floor by a family member.
With emergency surgery, the gallbladder had literally rotted when they found it.

in 2025 now, I have been experiencing the pain daily. I try several things to ease it, not much success. Drinking alot of water, abstaining from food (of course no fatty foods) hot compresses, rubbing the area a bit. This condition did not appear until a few years ago I have since gained 20 lbs because of inactivity due to the pain, although I still eat lightly.