So many cat problems, so little time!

I woke up yesterday morning with a couple little droplets of blood on my bed where Tara sleeps. I was checking her out to make sure she was okay, and saw that her rectum was bleeding. I'm taking her to the vet's tomorrow afternoon. Anyone have any idea of what might be the cause of that? I haven't changed her food or noticed her in any type of pain or discomfort. I've never had a cat with so many problems before. First conjunctivitis less than a month ago, and now this! What next?

Is she spayed??

Yes, she is spayed. That's what's so scary about it. I thought she might be going into heat until I remembered she was.