My cat has this strange routine with my robe. I leave it on the bottom of the bed every morning. He usually, when he gets tired jumps up on the bed and kneads the robe before falling asleep, but for the past few days he's been acting strange with it. He starts by standing over it then pulling the robe with his teeth so that it rubs over the bottom of him. He then walks with it between him until it falls out of his mouth. He sort of squats over it and rubs himself. Like a dog would rub themselves on a carpet. I'm worried it's worms, or is it something else? Any advice would be great.