CPK levels can be raised for a host of reasons. My neuro said that if you sit down in a chair too hard that it can raise your cpk levels, excercise can do the same thing. While high CPK can be an indicater of ALS or MS by itself it really means nothing....it is just a smalll component that a Doctor looks at to make a diagnosis.
If your doctors said you have BFS and you have had your syptoms for more than a few months listen to your doctors.
Paul