What Causes Pain In The Hip,back And Legs After Sleeping In The Same Position For A Long Time?

Hi, I am having pains in my leg the longer I sit on a low couch or anything low, hard or even sleeping in the same position to long increases the pain. The pain I believe is located in the hip and realises later in the back and legs. Massaging and streching the area only causes greater pain. Is this the result of nerve or muscular problems, which specialist should I see