My poor Ruby!
Did you examine her paw and each of her toes and pads or if she has a ripped toe nail, or a cut on her pad. Also very gently squeeze or massage up her leg to her hip feel for any warmth or swelling,and if you can move each toe, the paw, the hock, the knee, and the hip. Is she licking any spot on her leg? This will give indication of where she hurts. Could she have gotten frost bite? If it doesnt get better by monday or you cant find the problem take her to the vet. My dog sprained her tail, and it was warm and swollen and she wouldnt move it so I gave her an asprine, Never Tylenol (tylenol is toxic) and she was ok the next day. Good luck I hope Ruby feels better soon. Rosemary