Doesn't look like fungus to me, either. When you say a puff of fungus, can you describe it? Have you been treating her with any meds?
Fungus has longer hairy looking fuzz as opposed to bacterial which is more cottony; shorter tufts of cottony-looking lesions.
Here's a pic of fungus, and then the next two pictures are of Columnaris, which is a bacterial infection. The two conditions are commonly mistaken, one for the other.
Your Molly's lesion looks like a lump under the skin in the picture. Can you try to get more pics? Maybe this would help.
Like I said, a week or so ago, it looked like a round fluff ball. Now it's gotten down some and these are the best pics I can get. It's now flattened and 'matted' like real cotton balls tend to get after awhile. Treated with Kordon herbal Ich/Fungus and later QuickCure since other fish were acting sick and they perked right up after a day of very diluted QC.