Digestive Disorders Community

Hello WebMD friends! I have held off on posting here for help for a long time now, but it seems to be my last resort. As I've gotten older, I have noticed more and more that I am constantly feeling nauseous, light headed, and sometimes I get an extremely sharp pain in my upper left abdomen that lasts about 5-10 minutes. I am an otherwise completely healthy person, I exercise regularly and I eat healthy/clean foods. When I was in grade school, my doctor at the time thought I had Celiac, and I went on a gluten-free diet for about a year but nothing improved. I have gone dairy-free as well, and I still don't eat or drink any dairy. I have gone to my current doctor explaining all of the issues I am having and I was put on treatment for mono, which helped for maybe a month and then it was back to square one. After my mono retest came back negative, nothing had improved so I was referred to a gastro specialist, which resulted in my having a HIDA scan (to rule out gallbladder issues because my older brother had his removed at 17), an upper GI which showed no problems at all, and also an endoscopy which didn't show anything too concerning. I have been on medication for anxiety, and a few different ones for my nausea throughout the years, as well as natural supplements like magnesium and iron, etc., but still nothing seems to help! It has become such an ordeal now to the point where it's difficult for me to go through my everyday life. I can't go out to eat with friends or family in fear of having to leave early because the nausea gets to be too much. I have had to quit going to school and start online programs because I had too many absences from being sick (the rule was that if you throw up, you can't come back to school until 24 hours after, so I missed a lot of consecutive days when I had a really rough patch with whatever is making me sick).
It is really starting to take a toll on me mentally, because I am just so tired of being sick constantly. So here I am, crossing my fingers and hoping that someone on here might have an idea of what it could be that I could ask my doctor about, no suggestion is too outrageous, I promise! I just want to feel healthy again! Any Ideas?