In 2017, I was on the NCL Breakaway to Nassau. When I was on an excursion, I shared feeling ill and went to the infirmiry when I got back to the ship. Long story short, I had both pneumonia and sepsis from a leg infection. An ambulance came and took me to Doctors where I stayed for a few days to stabilize, then I was medevaced to Miami, where I was in the hospital for another few weeks.
Obviously, it wasn't the way I wanted to end my vacation, but I don't have major complaints with the way it turned out. I think the doctor on the ship might have originally misdiagnosed me, but he made sure to get me off to a regular hospital where they could do more tests. My biggest problem was that, while I had travel insurance and regular health insurance, Doctors didn't accept my health insurance, so I had to pay up front. Fortunately, I keep an emergency credit card for vacations, and they took that as a partial payment. I was able to get reimbursement from my insurance company later (ironically, I had a bigger problem settling hospital bills in Miami...bunch of miscommunication between my insurance and hospital.
While, all in all, it wasn't a fun time, I don't have any actual complaints about it.