mystery wrasse health problems

[asylumdown]

I recently obtained a very small mystery wrasse. It's maybe 1.5-1.8 inches long and when I bought it, it was in a tank at the LFS with a bunch of other wrasses of all types that were much bigger than it. It's tail fin was a bit tattered, something that I had hoped was simply the result of bullying, but two days after I got it in to quarantine, I noticed that 2 small patches on one side of it's body and one large patch on the other side were eroding badly. The erosion of it's fins were getting worse as well. I immediately began treating with Furan-2 and after completing the recommended 4 day course it's fins had begun to re-grow but the eroded patches of skin had not recovered at all. I then began a second dosing of Furan-2 with a supplemental half dose of melafix. It's now been a week, and it's fins have recovered almost completely but the eroded patches on it's body have yet to show noticeable signs of improvement. It's incredibly peppy, eats like a pig and other than the skin seeming to be lacking several layers in these patches, exhibits no signs of ongoing bacterial infection (no discoloration, condition isn't getting worse etc.). I'm just wondering if anyone has any experience in this area and knows how long I should continue treatment. I'm not going to put it in to the display tank until I'm confident it's well - if for no other reason than getting it out would be be next to impossible if it's condition worsened - but I don't want to be medicating needlessly.

any suggestions?