I have gastroparesis and I went through this exact same thing. What fixed it for me was going on a (clear ish) liquid diet for at least a day. I stuck with water and broth for a day or two then I started to slowly introduce bland food back into my diet and eventually I was able to go back to my normal diet. I still struggle with extreme nausea but I haven’t thrown up to that extreme since
endoscopy is the only way to rule out celiac disease. blood tests can give false negatives but it is rare! if you rule everything else out i would definitely ask for endoscopy. im sorry you’re going through this and have to advocate for yourself. it’s not easy to do especially when you’re sick
Towards the end of elementary school I was vomiting everyday. I was even accused of faking it. Turns out I had celiac and a peanut allergy presenting as only gastrointestinal issues, so eating a peanut butter sandwich for lunch everyday was making me really sick. It can be difficult to get doctors to listen to you but it doesn’t mean there’s no hope or that you should give up when they tell you things that seem wrong