My Night

I just had the most awful night with the cat. I don't remember the others being in quite so much pain. She hasn't been able to lie down or relax. She's sat up poker straight at the front door in the cold (a draught comes under the door). Everytime I've tried to move her she's cried out in pain. This morning she's collapsed and I laid her on the sofa and she's trying to sleep.
I feel so damn guilty for doing that to her.
I wonder if you can give cats painkillers?