Well, it sounds like you have the facilities to examine her. If you have not actually put your hands on her, throw her in the chute - run her up into the squeeze and do so.
Hip could actually be affected by a leg or foot problem. She may have been damaged by a cow riding her / vice versa during a heat. Doesn't always have to be a bull.
You do not metion size of animal as compared to others in herd - but even a light cow can damage a heavy cow in some instances.
Start at the bottom and work your way to the top. Feet, legs and so on. No obvious signs of rot, split feet, etc - then onto the legs and see what you can see.
In the end it is sometimes better to do nothing and let nature take its' course. Like Beefy suggested, it could simply be a sprain / strain.
If you find something obvious, doctor as required. If you find nothing and cow appears to be in discomfort, but not failing - eating and drinking well -then maybe I would wait for a day or two. If you find nothing and you are worried - call the veterinarian.
Best to all,
Bez
