That sure looks like ich to me. I'm a little unclear about what kind of QT tank you have her in. And heat is imperative while treating ich but you say she's in cooler water?
Is there any way to get her in a hospital tank with a heater? You can try to salt heat method but she's pretty well covered so you might want to go with a good ich med. Kordon's Rid-Ich is pretty good if you can get it locally.
I hate troubling you, but this one has me stumped. I think I may know what it is and what to do about it, but I'd like to be absolutely sure before I lose another one because I guessed and got the wrong answer.