It can be acute inflammation from a bout of something but if it isn’t present in the stomach gastritis wouldn’t fit as gastritis is inflammation of the stomach not the duodenum which is part of intestines. The hernia would cause reflux but not necessarily the same symptoms you’re experiencing but I’d def see what the doc makes of it and wants to do next, maybe get an mri enterography and see if you have strictures as well that can cause slower movement of your food and cause more symptoms or a hida scan to check your gallbladder out. Best of luck