My guess is that it is not lupus but something inflammatory, infection or autoimmune, is going on. It is a little odd that cpk is elevated that much in a young child. CPK is not normally elevated in lupus but is associated with other diseases that are more muscle related. Lots of possibilities.
Also, keep in mind that just because you test positive for an antibody associated with a disease does not mean you will actually get it. Most autoimmune diagnoses are made with a combination of labs, clinical symptoms and sometimes other tests. Never easy. Hope you can get the doctor quickly.
MCTD (SLE Lupus, polymyositis, scleroderma). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, barretts esophagus, quadriplegic in 2005. Recovered and now active in downhill skiing, golf, hiking. Meds: amlodipine, benezapril, omeprazole, potassium, folic acid, vitamins, maxide.
Remain Optimistic and you can overcome.