I Am 58 Years Old, I Take 3600 Ml Of

I am 58 years old, I take 3600 ml of gabapentim a day for nerve pain. I have been having stomach pain, diarrhea, bloating, feeling full for over a year. Recently had a stool test and it came back that I had severe enocrine pancreatic insufficiency. I had a ultrasound on my stomach and it came back normal. Can an ultrasound show normal and you still have epi or should I have an endoscopy ultrasound???