The symptoms you are telling suggests some disorder of muscles but not of Bone Marrow
, though a rationale examination is required to identify the exact cause of her problem. I would suggest you to straight away see your doctor for her check up. there are plenty of reasons any of whcih could be responsible for her problems. A few of which may be Myositis
etc. but only a proper clinical examination could establish some facts..
Wish her a speedy recovery to health