Is it mucus or dried shed? If it's mucus than your snake had an RI and needs antibiotics. In the meantime. Bump your heat a couple degrees and keep the humidity up. You could Also give her a warm soak in your bath. You a digital thermometer and have the water at 88.f. Keep her in the bath for 10-15 min and replace her in the cage. With stuck sheds they still tend to eat so if she hasn't eaten in a couple months I'm leaning towards an RI. Either way make a vet appt and get her in there.
Morgan