What Causes Assymetrical Legs In Babies?

My daughter is 3 years old and I have noticed that her left leg is assymetrical. She swings her left leg in when she walks and my sister (who is trained in sports rehabilitation) has said that her hip rotates inwards. I have always thought she was just very flexible, as she can get her legs in the most unusual postitions, but now I beginning to wonder if this is more. Could you please explain to me if it is likely that her hip is dyslocated, if so, would this have been present at birth or something that has happened at a later date. If this is the case where do I go from here and what would be the treatment. Not sure if this is relevant, but she was on steroids for the first 9 months of her life due to treatment for multiple segmental haemangiomas. Thanks in advance.