Prayers for one of my kitties...

Our kitty Venus (Slene as we call her) started pooping on the floor about a week ago. We've been perplexed as to why she's doing this. Anyway, today it had a lot of blood in it. I called the vet and she wanted a stool sample to begin with. I didn't even think to save it. So, I have her in our upstairs bathroom with food, water, and a litter box to collect a sample. Please say a prayer that she's ok. I'm worried. She's 8 years old and I don't want anything to be majorly wrong with her.