Please help! Urgent!

I need help!
My cat is a 9 year old Tabby and she is overweight. (I have tried everything. I limit her food and she is on “diet” cat food but does not lose a thing.)

Anyway. I am in urgent help for I don’t know what to do. It is Saturday and my veterinarian does not open until Monday morning and I have no clue what to do. Today my cat wandered into my room and laid with my on my bed. As she was laying on the bed she started cleaning herself like normal, but then I noticed that she was licking her anus for an unusually long time so I went and checked if there was anything wrong. Well, she has poo all over her behind and this brown black thing sticking out of her butt. I took a warm rag and pressed it onto her butt to clean the poop off her fur. As I did this it became red and inflamed and looked like it was bleeding! I cleaned it and let her go as she was angry and I just checked up on her again. The profusion is in fact not on her anus itself but next to and below it. Please help me. I would take my baby to the vet but they are not open and there are no animal hospitals in my area. I don’t know if this is an urgent matter or if keeping the area clean will be enough until I can take her to the vet in Monday.