Cat anus bleeding and he refuses to sit down, looks in pain

My cat got back today from going out and he looked abit in pain, he came and sat next to me and i noticed abit of blood on the cushion, He wasn't sitting properly either, he looks like he is in abit of pain but there isn't alot of blood 

I'm sorry your cat is in pain. I would call the vet and get him checked.

I hope all is well soon.

It's sunday, the vets here arn't open until tomorrow

Does it appear to be a cut on the outside or blood coming from inside him? This would make a huge difference in whats going on. Is the blood bright red or dark? I would look up an emergency vet open on weekends and get him checked out.

I think a vet trip is the best thing especially with you saying he is in pain, they can let you know the best thing to do.  Maybe ring an emergency vet see what they say whether you need to get him straight in 

 for him!

my cat did this. It started late at night. I got him to the vet very early the next morning. He was dehydrated from refusing to drink anything. He was getting better and was going to do exploratory surgery but : ( Anyways I wanted to know and so did the vet. He had a string like from clothing that was not passing got irritated then septic.