I will get some AC tomorrow.
I would save some of the plant to show at the emergency doctor. Rinse my mouth (or wound or other spot where the plant entered my body), cal 112 and ask advice on what to do while waiting for their help, vomit yes/no, AC yes/no, finding an antidote yes/no (probably no as there is a risk for a second mistake).
Then I probably try to distract myself to remain calm and not mentally create more symptoms than there really are. I know that moving physically helps me to releave tension so I would try to do some (not to heavy) physical movement, staying at the place that I mentioned to the emergency help.