There could be sulfites in the salad dressing. Do you have the same reaction when you eat salad at home?
I woke up one day last week feeling like my throat was closing. I took a Claritin and a Zantac and then tried to figure out what it was. My skin was slightly red and my scalp was itchy. So, the best I could come up with was that I had worn wool 2 days in a row. I bought 2 new merino sweaters, not from Ibex, more fashion type sweaters. One seems very itchy. I also had worn my Shak around this time. Last March I seemed to develop the same type of thing, but even worse, so I took Claritin for a couple of weeks, and then eventually it got warmer, so I was wearing less wool. Since I am not giving up my wool, I now know to give my body a break from the wool that seem to set me off more than others. I also was not feeling well, in general, so it might have just been my usual strange response to illness.