Hi, The pain in your left leg, hip, and knee area could be due to a variety of factors, including: * Iliotibial band syndrome (ITBS): ITBS is a condition where the iliotibial band, a thick band of fibrous tissue that runs along the outside of the thigh from the hip to the shin, becomes inflamed and causes pain in the knee, hip, or thigh. * Hip osteoarthritis: Osteoarthritis is a degenerative joint disease that can cause pain, stiffness, and loss of mobility in the hip joint. * Knee osteoarthritis: Osteoarthritis can also affect the knee joint and cause pain, swelling, and stiffness. * Sciatica: Sciatica is a condition where the sciatic nerve, which runs from the lower back down the leg, becomes compressed or irritated, causing pain, numbness, or weakness in the leg, hip, or knee. * Muscle strain or sprain: Injuries to the muscles, tendons, or ligaments in the leg, hip, or knee can cause pain and swelling. A doctor can properly diagnose the underlying cause of your pain and suggest appropriate treatment options, which may include physical therapy, medications, or in some cases, surgery. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Priyanka, General & Family Physician