What's wrong with my cat?

She got outside and was out all night; it's kinda cold and rainy and I know there were some stray dogs running around. She showed up on the porch this morning. She barely moves and won't let us pick her up. She acts sleepy and like her stomach hurts. I'm afraid she's broken a rib or ingested poison or something. We're going to get her to the vet, but do you know what it might be?