You know, Megan... I have a severe hiatal hernia.
It was found during my last upper GI. ( I have had 3 over the last 40 yrs).

During it, the doctor got animated and made me drink a second
cup of that awful stuff..the barium.

When I got the results at my doctor's office she also was excited.
She said it is pretty rare for hiatal hernias to show up on Xray.
Less than 10% do. Mine did. They made me swallow crystals of like BromoSeltzer dry... to blow up my stomach with air. I can say it was NOT PLEASANT.

I have this congenital twisted GI tract that I was born with.
I had never had a hiatal diagnosis before. But with those crystals, the radiologist saw my stomach move up. So he had me lie on my right side, sort of on my stomach during the Xray, and I had to suck up the second cup thru a straw and swallow when he said to. (my stomach is twisted 90 degrees and empties in my back not in front like most other people).

My doctor thought my hiatal hernia may be part of the birth defect. But then she said all the vomiting I have had to do (sorry but it is graphic) over the decades could have torn it as well. Here in the states, they do not recommend mesh repairs any more. So do research that if you are offered. She told me at this time not to have any surgery, and just live a conservative life style which I do anyway.

What are your symptoms? I'll tell you, I've had a bundle of them over the decades of my life. Right now I have not had a spell of vomiting for several years. Going gluten free for 3 yrs helped and now I am fructose free and even BETTER.

I have to avoid all gaseous foods (cabbage is a killer for me), and rarely drink any carbonated drinks. I might have one here and there, and I let most of the bubbles go away. I use Beano for every meal with vegetables. And Lactaid milk or lactase tablets for regular milk or ice cream. That has helped too.
GAS is a killer! at least for me.

Kmeb can help you with gastroparesis issues. But be sure you really have that. Sounds to me like they don't know. Not a good place to be in any case.