African Spur Thigh has a swollen back leg.

I have 3 African spur thighs age range from 2 to 10 years old. My middle one is about 5 years old and she has a swollen back leg up near the hip joint. she is eating fine, but is limping around. They all live in a outdoor enclosure, so they get plenty of exercise, sun and shade. I do notice that the 10 year old, does push her around sometimes, so do you think that he may have hurt her?