I am going with a liver problem, The A.L.T. and A.S.T. and C.P.K enzymes are a dead giveaway. But like every medical mystery things just get deeper and deeper. I would have so many other questions, diet,emotional health, mood swings anything would give us a clue. I guessed celiac's or a type hepatitis right of the bat, but the article seems to dismiss those. This comment make a lot of sense but does not deal with a muscle problem.
"Let's try something that would make the exhaustive, expensive evaluation appear unnecessary in the end. How about traction alopecia from wearing her hair in a ponytail, with the elevated CPK and hepatic transaminases being an unfortunate red herring"