I had the same exact problem a little over a year ago. I was 17 and experiencing the same problems and none of the tests came back for anything. The only ting that was obvious was that my CK was elevated. My best advice is to stand by your daughter. I had a hard time because everyone thought i was crazy and that only made it worse. Also, i wouldnt let them put her on any corticosteroids unless they know for sure because they just treated mye with prednisone and it only made it ten times worse and on top of that the drug has some horrible side effects that can affect your self esteem, especially considering that shes only 17 as i was. Eventually it went into remission and im hoping that it doesnt return. Just wait it out. Hope i helped