My female rabbit is pulling her fur out?

my bunny (poppy) lives in my office, but has the run of the outside all day long she only sleeps in the cage at night, yesterday morning i went to let her out and i noticed a nicely formed bundle of fur about the size of a golf ball, she has never done this before and i was wondering why, i brought a 10 week old female rabbit 2 weeks ago who now lives with my poppy, they are the best of friends and do all the loving things Bunny's do 2 each other, but the really worrying thing is i was checking her litter box this morning and i noticed a tiny as in smaller than her poo, piece of clotted blood and now im worried, but she is really bouncy and happy and eats brilliantly so im a little confused! also this morning she was doing some honking noises when she was in her litter box, i don't think the blood was from today though because it was dry, she hasn't been spayed,