The only thing that comes to mind is that the tufts that are loosely attached to the sin or floating in the water is a form of water mold ("fungus") known as Saprolegnia. It is a fairly common infectious disease among clawed frogs. These molds seem to be a secondary skin infection of injured or debilitated frogs. Water mold is often associated with water that has a high level of organic material (waste from frogs or fish as well as uneaten food).
FYI - Often fish will transmit this disease to the frogs that's why you shouldn't keep aquatic frogs and fish together. I am not sure if you keep fish and frogs together.
Without pictures, it is hard to make a diagnosis. Here are some of the signs of this disease: lethargy (fatigued, lazy, listless); grossly visible grayish-white tufts loosely attached to the animal and mats of these organisms can be seen floating in the water. A salt bath would be an appropriate treatment, if it is water mold. I would tear down the tank and completely sterilize everything before putting the frog back in. Good luck! Jenna is our other clawed frog expert.