I'm not sure but I will offer two suggestions: The first is that the area remains sensitive after the yeast infection. The second is that you're itching down there because you're worried you have something. You certainly don't have a fungus (there would be a rash) or scabies (entirely different presentation.) I suggest benign neglect.
I can't think of any relationship between intercourse and yeast infection. Are you absolutlely sure that's what you had, or was it self-diagnosed and treated?
I think a doctor's visit ofr diagnosis and reassurance is in order.
Best.
Dr. Rockoff