...let's put it this way; she was extremely horny and responsive,  but I noticed something powerful in the air, and it was NOT pleasant. It was as if a fishing trawler on the high seas had broken down and the ice had all melted.  Then the crew all died. Then ANOTHER fishing boat with the same fate had crashed into it.  I'd like to keep seeing her. She very hot and fun to be with. She says she's a doctor too.  How on Earth do I broach this subject? Via text, phone or in person?  I dread the embarrassment  this can cause.

If it was as bad as you say, I would have already let her know she needed to improve her hygiene.