Like Milfnextdoor, I would be ethically obligated to call and stay with the person. Since ALL my clients are undressed on my table, I would (as always) make sure that they were properly draped.
After calling 911, I, too, would probably give them an aspirin, make sure I am properly dressed before the EMTs arrived. I don't know if I would go to the hospital or not but I would make sure that the EMTs had my contact info.
I hope this never has to happen to anyone. As a side note, the medical crew DOES need to know if the patient has taken any "enhancement" meds so keep that in mind!