I had an attack today, whereby I could not swallow very well; it felt as if something were stuck in my esophagus . I started hiccuping, and then started vomiting up whitish foam. I was at a store, and went to the bathroom there; continued to spit up. I left and came back to work, and immediately threw up whitish foam. Is it an allergic reaction of some sort? I was in Costco and sampled the food - nothing particularly unusual. Any ideas?