See your doctor. Hip ache at night time could be many things. First, make sure you're not always laying on the same side and compressing a nerve. Are you stiff or your shoulders hurt too? Then consider things like polymyalgia rheumatica. Sometimes, night pain in bones can mean something more serious like malignancy (especially if only on one side). Bottom line, if not going away, see your doctor. Good luck!
Get checked! It's hard to determine without a complete history and examination. The hip joint is a ball and socket joint and its motion is controlled by surrounding muscles and tendons. The surface of the joint is covered with articular cartilage. Your pain may be due to an injury to any of these parts. You could have a tendon or muscle strain or tear, a ligament sprain or tear, or damage to joint cartilage.