This has been bugging me for a while, the story opens with an aunt? or grandmother locked in a bedroom because she is sick with something we would think is minor and there are no more antibiotics left that work. The mom basically leaves food for her to see if she will survive the infection. The story mentions how the narrator can hear the woman begging and moaning through the door for help.
Contemporary setting, dystopian feel. The mom in the story trades alcohol? something contraband? on the black market to acquire medicine from the town doctor (who I think is killed later in the story?) I recall that the mom was worried about her own daughter being ill which is why she was trading with the doctor. I think they met behind a bowling alley?
I thought it was written by Nancy Kress or Connie Willis, it has that near future "what-if" style they have. Think when Nano Came to Clifton Falls.
I believe it was in an anthology (maybe the Dozois Best Of one) from the 90's or early 2000's.