Hi this is Dr. Gabby. Most common injuries with what you are describing would be a knee injury or a hip injury. As long as she is putting weight on it, and you do not see any swelling, it can wait until tomorrow to be seen by a vet.
If she is not on any medications and she does not have any underlying health issues you can give her human aspirin for pain or inflammation.
5 mg of aspirin per each pound of dog every 12 hours.
For example a 10 pound dog would take 50 mg of aspirin every 12 hours.
Give it with food to help prevent gastrointestinal upset.
Try to get her to rest.
That means no jumping, running, or playing.
If she is not back to normal tomorrow and using the leg well ten she should see a vet.
Emergency clinics are open 24/7 if she gets worse or you want to locate the site of injury today.
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