Have you considered that you may have acid reflux? When acid seeps from the stomach to the esophagus, you may feel nauseous. Acid reflux doesn’t always burn. This has been my experience. I take an over the counter acid reducer like Pepcid, but you may start with an antacid like Tums. Anxiety can make your symptoms worse so you might ask yourself if you see a connection between what you experiencing and stress.
I pray you are able to find the cause. I can relate to your situation.