Hi Carrie, welcome to the forum.
I'm glad you started your own thread in addition to reading others.
The only way you can be sure of a sulfite allergy is to keep a food diary (food log, journal, etc.) That will give you the general foods that cause you problems. Then you have to break down the foods into the components.
Even after identifying foods, you can have a sensitivity to textures. I am starting to note my esophagus rebels at dry foods, probably because I don't make enough saliva, which is because of meds I take.
Garlic, and especially onion, have sulfite naturally. Pepper has some because of the way the peppercorns are roasted.
Broccoli has .47 ppm, cauliflower .3, cabbage .35, eggs about
1 ppm, according to Rick's table in his book on paper. I didn't easily find garlic salt or kale, but they're sure to be somewhere. If you go to his website and read the free online book, there is a formula for calculating the amount of sulfite from the weight of what you ate. http://www.learningtarget.com/nosulfites/index.htm
For a guestimate: weight of food in grams x parts per million = micrograms of sulfite
Read the book for a better understanding. I tolerate about 2000 micrograms a day, which is not bad.
Sulfa drugs are not a problem for me, but they are for may who are intolerant or allergic to sulfites. Since you have a throat closing problem, I hope you are not in the category of true allergy.
If it were me having what I thought was a true allergy I'd take a Benadryl or half an Alevert. But I'm not a doctor, so I am not telling you what to do. If I had a life threatening condition I would certainly go, and have gone, to an ER!
If you can find an experienced allergist, one who believes in sulfite sensitivity, it would be a good idea to see if you have allergies (scratch test) to any foods. I know I have allergies to sunflower seeds, some pollens, dust ... Allergies can come and go. I feel lots better when mine are controlled with weekly shots. Too bad there isn't a shot for sulfites! Or sunflower seeds! My allergist was the one who got me keeping the food journal.
There has to be some other problem if you are also having trouble with reflux. If your LES (lower esophageal sphincter) closes appropriately you can't get stomach fluids into your esophagus. I'd see a gastroenterologist, and I did. I had a small problem, but controlled the acid with medication for many years. I found that sulfites "triggered" my stomach into heaving, forcing contents into my esophagus. As long as it was not acid I didn't have a problem. I stopped eating snacks at night slept propped up a little, and didn't even have nighttime problems. [After getting things under good control I was in an accident which forced my stomach into my chest. Then I needed the surgery.] You might ask your gastro doc about changing to another PPI. I only had good luck with Nexium and one other. The OTCs were not long enough lasting.
I still have heaving (what I call refluxing) of my stomach if I eat too much trigger foods. The contents can't come up, but my other reaction, tachycardia, still occurs, and it's dangerous. I don't need acid reducers anymore, but don't recommend the surgery unless it's necessary. The surgery does nothing to cure sulfite sensitivity!