It could be an internal infection, the torn area may have become infected and is now showing signs of Ick due to the stress. feed lots of garlic and give a FW dip You have to QT her. You may try medicating her food and water in the QT. An anti-biotic maybe someone that is familiar with the medications maybe able to give you some added info. I would use a broad spectrum medication. If her gills are not looking very good a FW dip will help in this department also a lower SG in the QT will her her get needed oxygen. Also raise the temp in the QT to 82 this help to speed up the cycle of Ick and other parasitic infections. If when you do a FW dip you see flukes come off her then Prazi-pro is the best med to help her out. It does not seem to bother the fish, corals or inverts even. Nem's close up and loos a bit of mass. But they come back from the treatment. You have to run the whole 7 day treatment it works better and normally you do not have to retreat the fish or tank.

If she looks like she has a dusting of white or gold powder on her then she has Marine velvet, only treatment is Copper and you have to treat all fish she was with. I would prefer to treat the fish in separate tanks. This helps to stop any fish that has not contracted the MV from actually getting it from the sick fish while in treatment. The tank would have to sit fish less for 3 months to get rid of the MV in the tank.

Anyways I hope this helps and we are not to late, can you post some pic's
Bill