I would definitely isolate her, if you haven't all ready.

I assume you just noticed this bulge. Would you have noticed it if it was there a week ago? A month ago? If it has arisen slowly over time, it may be tumourous, and there's not much we can do.

If it looks more like an ulcer (full of pus, redness around or in the middle of it), then you should consider treating with an antibiotic, like kanaplex, or the combo of Maracyn I and II.

As well, I'd like you to check for velvet.

How are your params?

~Ash