I've had pain in my left hip when I sit for about 6 mos now, what should I do?

See a specialist... Hip impingement or femoral acetabular impingement is a diagnosis that encompasses a bony or mechanical pinching at the periphery of the ball and socket hip joint. One of the common symptoms is pain while sitting because of the flexed position of the hip. You should see an orthopedic hip or sports medicine specialist trained in hip pathology to evaluate your specific condition.
See a specialist. See a non-surgical sports medicine specialist, who can sort out what may be the root of your problem. It can be anything from tendinitis to hip arthritis.