Time will tell whether it is an injury or not. I have had two different hens limp for a period of time. One held her leg up for 6 weeks, and got better with no treatment. Another limped for two years, but she fiercely wanted to travel all over my chicken field with her friends, eating, and roosting normally. But eventually, she would only go with the flock and lie around, losing weight, and I never knew the reason she died. I suspected a spiral leg fracture that never healed, but without xrays or a necropsy, I could only guess.
It is controversial whether to medicate of not, but many give aspirin in the water to help with pain. Some believe that pain relief might have them overuse the painful leg. Meloxicam from a vet is also used for pain and inflammation. Please let us know how she does after resting her leg if it gets better, or if her symptoms get worse.