Hello and welcome to the forum. We appreciate your question but are sorry you have had this issue! Do you have a regular care provider? I read that you went to an emergency room and were told there was nothing else they could do. I'm wondering if you misunderstood. An emergency room is for acute situations. They basically patch people up so they are well enough to go home and send people on their way. Any ongoing situation is not their area to diagnose and care for. You had no acute situation they could care for but that does not mean that your pain is normal and there is nothing to treat. That is my guess, that is. Working with your own doctor, general practitioner is important. And if they are not able to find the cause, a specialist such as a gastroenterologist would be ideal.
I'm glad you have gained some of your weight back but see you have a ways to go. Do you actually still get the stomach pain and nausea after eating or are you not sure because you limit what you eat to avoid that? Do you keep a food diary where you record what you eat and when? This is a good idea to give you a picture if your symptoms are related to diet choices or any intolerance to specific foods. Another area to investigate is if you have ulcers or GERD, both of which could cause your symptoms. Gallbladder issues and pancreas issues can also cause problems like this and a gastroenterologist could diagnose this. And do you suffer constipation at all? And vascular problems or narrowing of the arteries could also cause this. https://www.medicalnewstoday.com/articles/317628.php
There are lots of possibilities. Do you have a regular physician you can see?
Look into Exocrine pancreatic insufficiency (EPI) treatment like CERON. Ask your Dr./GI. It helped me for the pain & nausea after eating. and loosing weight. Good luck,