How can I find a diagnosis for my aunt with leukemia and muscle pain - doctors can't find anything wrong.?

My aunt was diagnosed with leukemia 5 years ago with relatively few symptoms. As of 1 1/2 years ago, she began having muscle pain and weakness. Walking along, her hip would suddenly give out. She will at times lie in bed crying without any solution. She doesn't take any narcotics but has been living on Motrin. Her doctors say they can't find anything wrong with her and make her feel like it's all in her head. As she doesn't have a diagnosis (because they're telling her it has nothing to do with her leukemia), she can't get disability and has to continue to work as an elementary school teacher, now using a walker to support herself. I'm going to try to get her to come here to John Hopkins for treatment and answers but I was wondering if anyone has heard of this before related to leukemia?