Knocking on rear passenger corner

[Gazza1379]

So I've got a knocking coming from passenger rear, assumed it was a wheel bearing but mechanic wreckons it's the spring knocking on the Shell because the previous owner put lowering tein springs on the standard shocks but my I'm not sure because it only does it on that one corner and I've had the car 3 years and it's only started the last couple of weeks, surely if it was because of the springs it would have done it since I owned the car? Any thoughts