There have been quite a lot of people here over the years who have adverse reactions to substances used in exams - from fluorescein dye to dilating drops.
What I would do:
1) Call and let them know specifics. You'll want it put in your record so your dr. sees it next time he pulls the chart. And...
2) At the next appointment, if the technician wants to put anything in your eyes before the doctor sees you, ask them to please NOT do so until you've seen the doctor. If they voice any objection, that's when it's really handy to be able to say, "It should be in my chart. I called after the least appointment to let the dr. know I had some trouble after the last appointment."
The Dry Eye Zone