About 3 hours after I landed. Blood pressure 180 over something (normally I'm normal!), temp above 38.
Sure, there's not much you can really do in the air, you can't get hold of paracetamol or anything that would have helped.
Don't get me wrong, the treatment by the crew was OK but they were direct with me to the point of being blunt. Clearly, they assumed and said it was self inflicted, and just wanted me to not-be-their-problem.

Would I have boarded if I knew I would be ill? No. But I assumed it was a slight cold. And how often have we all flown with a not even a full blown cold, just a slight snuffle?

The point I'm really trying to make is that if a passenger specifically says they are unwell, or if they are not totally conscious, please ask or just keep an eye on them. If I had had a heart attack I suspect no-one would have noticed.