Lace Crater (2015) on Netflix

Plot summary

Ruth is a young woman in her mid-twenties who is awkward and lonely, and she has had too much to drink. She has gone to the Hamptons for a weekend with friends, and she chooses to sleep in the guest house, a place that is said to be haunted. Michael, a ghost draped in burlap, appears casually in front of her, and the two of them start talking. Their talk leads to a sexual encounter. Ruth comes away from it with a sexually transmitted infection whose effects are alarming, and her body begins to go through a series of strange physical changes.