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It seems that you may be having a pain due to sciatica. Sciatica refers to severe pain, weakness, numbness, or tingling in the leg. It is caused by injury to or pressure on the sciatic nerve. Sciatica is a symptom of another medical problem.
Common causes of such pain is due to slipped disc, pelvic injury or fracture or degenerative joint disease. Elevated CPK levels are usually associated with inflammatory myopathy.
You can try to control the pain by application of heat or ice. OTC pain killers (Advil or Motrin will also be helpful). In case it is not helping antidepressents (amitriptyline), gabapentin, lyrica and duloxetine are a few medications that can be prescribed by your doctor.
Other measures that may be helpful include physiotherapy and back strengthening exercises. Avoid heavy lifting or twisting of your back. This should include exercises to strengthen your abdomen and improve flexibility of your spine.
You may consult with your doctor who can examine you and provide you proper pain killers and medications that help to control the pain (as mentioned above). A referral to a pain clinic can also be requested by your doctor.
I hope this helps.