One of our belties is about 3 years old. She gave birth to twins prematurely June of 2014 & we lost one of them. She was with a bull for a few months after this & we are not sure if she ever got pregnant-she never looked like she was getting bigger....about 3 weeks ago (beginning of May) she went lame & favored her front, right leg. Since then she looks like she walks normal but her lethargy has increased & she continues to lose weight. Any ideas of causes of these symptoms would be greatly appreciated.