Weirdest noise problem I had while pedaling, and I don't think this is your problem was counterfeit chain. I had bought a 11 speed Shimano chain on eBay and discovered it was a counterfeit and it was just slightly off in spacing or size or something cause it to jump ever once in a while in my jockey wheels.
Anyway, my suggestion are above. Get your torque wrench, lube and carbon paste out and just do a thorough tune up.