Hi,
Sorry to hear about your problems. Did the endoscopy show anything?
It is just possible that you have something like a hiatis hernia or at the other end, which is the pyloris muscle that is interfering with you digestion. The back pain is probably referred pain, but if your belly is also bloated, then this maybe related to something lower down in your intestines.
Go and discuss it again with your doc and see what he says. Hopefully your endoscopy may show something.
Let me know.
Cheers
Sarah