Something similar just happened to me yesterday. Flying through MEX from EZE to YYZ. All was fine until we boarded the second plane, to Toronto, and then I was overcome with such sudden nausea, I had to run at full speed to the bathroom. After copious vomiting, I went back to my seat, to tell my girlfriend I think we should get off the plane. Before I could get those words out, I had to run back to the bathroom, and vomited again.

The second I emerged from the bathroom, we were told to get off, by the flight attendant.
We were told by the gate agent to grab a seat and wait while they got us sorted for the flight.
And again, I had to run. No bathroom nearby, so I had to run to a garbage can.

Vomited again, and again, and again, into this trash can. After the 5th bout, I collapsed to the floor. And continued to be sick, on the floor for a half hour while waiting for aeromexico/airport staff to come.


Not one of my finer moments, at all. Eventually help arrived, my vomiting subsided, and we were brought out of the terminal, to re-book the flight and get a hotel. At no point before this became catastrophic, did I have any indication of being sick. Nor was I inebriated.
Cost me 2k in flight changes and hotel bookings.

Fever started a few hours later.