I will assume you do check the oil level regularly and change it from time to time? As a rule noise is never a good sign for anything mechanical even if the item seems to be working fine, noise is sometimes the first sign of bad things about to happen. A good start might be have a mechanic have a look at it. If taking it to a mechanic is not possible drain the oil and look for shiny particles, almost like mini sparkles....if you see those sparkles the damage is probably already done and it will fail sooner than later. Best of luck getting her back to normal asap.