Peeing everywhere...

Hi all - my kitten has been peeing on everything, even though she's litter box trained! At first it was just two things (a blanket and a cat bed) I had gotten from a friend who has a cat, so I thought maybe she smelled the other cat. But she peed on my bed last night while I was sleeping in it. I've had that blanket on my bed for a while, so I don't know why she would choose to pee on it now if it had to do with it smelling like another cat or something.

Any ideas? I really don't know what to do...