@daughter .. Your first description of his pain made me think diverticulitis, but it would have shown in the tests you described he had. I wish I could help. I deal with nausea quite a bit with all my stomach and esophagus problems. Zofran sometimes works amd sometimes does not in quelling it. I spent 17 months on a feeding tube. It might be an option for your dad. There are various types I had a 24 hour pump.. as I went back to food I disconnected it during the day and did my feeding over night as instructed. Some people use a syringe feed method. One thing I liked about the Mayo Clinic in Jacksonville FL when I was so sick was they worked as a team to try and figure out how to best treat me.

Heart doctors would know if his pain might be what they call referred pain. Continue to be the good advocate you are for your dad. Get second, third.. fourth opinions if needed. Please keep us updated.

I will keep y'all in my prayers.
Zaroga