Which tests can be done to confirm hiatal hernia?

Hi doctor,

I often get nausea and vomiting sensations for many years. This started after food poisoning, and I take Domperidone 20 milligrams daily to get relief. I was hospitalized (ten days) for Influenza, and a Ceftriaxone injection was given for ten days, and I was coughing badly. Later I had pain just above my stomach and at the center of my lungs. This pain used to come right after having meals. I was given Pantoprazole and muscle relaxant injections, from which I got relief. But after getting discharged from the hospital, I started to get extreme acidity. I also started to get recurrent food poisoning that got resolved only after taking strong antibiotics like Amoxicillin and Azithromycin. Since then, I have been on a strict diet, and I cannot eat without restrictions like I used to do before because I get nausea and vomiting (especially at night after dinner), and I need to take antibiotics to get relief. I was also diagnosed with GERD, and I got relief after taking gastro-resistive Rabeprazole, like Rablet. However, I cannot take such a PPI drug for a long time because I get diarrhea and infection. Therefore I need to know whether the problem is because of GERD or any other reason. Could it be a hiatal hernia? My endoscopy with biopsy and sigmoidoscopy are normal. Do I need to do any other tests? Please help.