Just noticed this at what I would call the nape of the neck on one of my does. She hasn't had contact with any other rabbit, so it's not a bite. It's just behind the ears, in the fold. Maybe yeast/fungal? Mites? Not sure. I wouldn't have noticed it had the fur not had that little bit of tinging. The spot I saw looked to be about the size of a quarter. Not sure to try Blue Kote or DE - maybe both? I have Ivermectin and PenG as well (assuming they are not expired).