There are 3 things that make a dog not put any weight on a leg: a broken bone
, infection, or a tumor.
How old is she? If she is young, a tumor is unlikely, and bone cancer is rare in this breed.
Can you take her temperature with a rectal thermometer? If she has a fever, over 103, this may be an infection and she might need antibiotics, pain, and anti inflammatory medication.
If she were mine, I would take an Xray. Until you can get her to your veterinarian to be examined and maybe Xrayed, you could try aspirin: 2 baby or low dose aspirin twice daily, with food. If she vomits, do not repeat it.
If this is an infection, warm towels are good. If this is a sprain or injury, I would recommend ice or cool towels. If her body temperature is normal 101 to 102, I would try the cool/ice compresses.
Let me know what else I can answer or help with.