Elegance Sick

I got an Aussie elegance 3 weeks ago and it was doing fine. Was feeding it small pieces of fresh shrimp. Wednesday I was going to mix up the feeding a little and gave it a small piece of silverslide from a pack that was in the freezer. It ate it fine but by Friday it had all sorts of mucus looking strings stuck to its sides. They are gone now but it barely extends its tentacles. None of its flesh has separated from its skeleton. Could it have been the silverslide or just a coincidence? If it was the food is there anything I can do? Sure hate to lose this thing!
Thanks.