Daniel W.
The same thing happened to me twice with salads. I though the first time was just by misfortune, but not the second time. I have been allergic to cooked salmon all of my life and once in a while, a chef will put cooked slamon into food for flavor. My throat closes and my tongue swells up. Raw salmon, such as in sushi, does not bother me at all. So your problem may not be the greens in the salads but other flavorings that are added. Mine happens to be cooked salmon. Daniel.