Interesting you should mention artificial, since I recently a couple of times had nausea from lite activia and spoke with dannon about it and the only difference they could find between the non-diet activia I normally eat and usually have no problem with and the lite was an artificial sweetener!
Hope this helps. I had a 13 year old son who started with constant nausea day and night.
We put him through all the gastro-tests available including stomach biopsy. They checked him for celiac as that runs in our family. Nothing showed up. They kept going down the road that maybe he had issues. This was my most outgoing, well-adjusted child so I knew that was not it. Finally we went to a naturopath and she took one look at him and we finally started down the right path. Turns out he cannot tolerate any and I mean any amounts of preservatives and chemicals in foods. Take a look at a label on any prepackaged food! We became label readers, he only ate organic and plain food, no pop, only pure juices with no colouring and lots of water. We found an organic butcher so his meats had no preservatives. It was so bad that if you made a sandwich with a meat with preservatives you had to use a clean knife to cut his sandwich to avoid cross contamination. It didn't take too long to see a change. It has now been 4 years and he is much better. He still eats as healthy as he can but if he gets a bit of cross contamination the reaction is not as severe, he tolerates more. The amazing side affect for him is he maintains a very slim build, doesn't gain weight even though he was a very inactive person during all this. No junk food! MSG was his worst chemical trigger but sulphites and nitrites were the next ones as well as Tartrazine (Food Colouring) and even cereal package preservatives listed at the bottom as BHT. Hope this may help you.
Were you tested for celiac? Lactose intolerant? Any other posable food allergies? I get nausea a lot and I found that the best (and easiest thing to get) is Benadryl. You can find it in most drug stores...well all drug stores I think. the active ingreadiant is Diphenhydramine. Its also found in drugs like Ibuprofen PM. Just if you need something to help before you make it to a doctor again.
Did the doctor also take pictures of your gallbladder? Do you have a hyperactive gag reflex? Could you be pregnant (not sure if you are male or female)? Are you an anxious person (because that can potentially cause nausea)? Was there no evidence of gastric reflux when the doctor examined you?
Welcome to the gastroenterology community! What other tests has your doctor run? Has your doctor performed an endoscopy or blood tests?