Hi Buttercup -
I posted to you on the CP forum.
I believe you that you weren't faking. You're just young and inexperienced and haven't learned to tolerate some of the awful treatments we have to endure. Been there myslef, raised 4 sons, now teaching the mother of the grandkids. In time we do a lot of things that are impossible the first time we try.
For emergency nausea and vomiting help you can take a tsp of Paregoric, if you can get an (usually older) doc to prescribe it. It works instantly. I keep it on hand. No pill will do the same thing. It tastes awful, and it shouldn't be used daily because it's a narcotic. Did the stuff the ER doc give you smell and taste like licorice in alcohol? That may have been what they were giving you. (It's got anise.) If you can get it down for even a second it will stop the reflux and vomiting!
The ER also has a mix of other stuff that works, tastes bad. It seems intolerable but if you decide no matter that it might come back up you will just close your eyes and swallow it quickly, it really will work. The ER doc was frustrated. In a way, trying is psychological. When the nasty stuff works your mindset changes and you can take it again if you need to.
For home hydration, your grandma (and I'm in that category) knows that Vernor's Ginger Ale sooths, rehydrates, and will stay down when no water or coke syrup or anything else will. It has to be that one brand! It's lots sweeter. You can warm it and stir a little to get the bubbles out if they are a problem. I recommend it without ice. Don't dilute.
Go see a gastroenterologist!!! You need tests, lots of them and not fun either, to find out what's going on.
I've posted lots of time about keeping a food log to find your trigger foods, if there are any. It's a really important thing to do that will help your doctors. If they can't find something seriously physical they can see, you have to provide information. Keeping a log in a notebook with date, time, every bit of food and drink you consume and any reactions after a half hour, an hour and 2 hours, could point to a cure.
My list of foods was really weird: gelatin, cheese, soda, pork, maple syrup, anything with corn syrup, lemon or lime juice .... They all had 1 thing in common - sulfites. There are lots of good websites about food allergies/intolerances/sensitivities.