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It seems that you may be having a pain due to sciatica. Sciatica refers to 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.
You can try to control the pain by application of heat or ice. Try ice for the first 48 - 72 hours, then use heat after that. OTC pain killers (Advil or Motrin will also be helpful).
Other measures that may be helpful include physiotherapy and back strengthening exercises. Avoid heavy lifting or twisting of your back for the first 6 weeks after the pain begins. You should start exercising again after 2-3 weeks. 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 (Gabapentin, Pregabalin, Duloxetine, etc).
I hope this helps.