Cars make weird noises. I just had a hard to track down and very disturbing noise coming out of my old 'vette. A sharp metallic tapping down very low in the motor, like in the oil pan. Only happened when the car was warmed up and I'd hear it when sitting at a light next to a car or something else for the sound to bounce off of. I was worried, thought it was the kiss of death. Easy fix - just a loose dust shield.
An oil change at a real shop not a quickie drive through would let a real mechanic take a peek. Might be something simple, often is. Good luck with it.