Have you tried washing it off? Even some of it if it comes off will tell you its not YF-- that word is to me is dreaded I am sorry--- if it does not come off and it starts to spread to different areas there is stuff you can get to start treatment but that would haft to come from Tracie Drache613 or AHBD can tell you what to get --- so keep an eye on it this stuff is bad news if its YF-- and she would need to go back to the vet
Karrie
Karrie