Since it's rhythmic to wheel rotation, it's likely to be the pads moving against the caliper bracket. Hit the brakes, and the pads stop moving.
Try this stuff, you only need to coat the contact areas: Disc Brake Quiet

 

Thanks! I'll pick some up today. Do I use this in addition to the caliper grease I already applied or should I clean everything off and start fresh again?

 

Clean the grease off. The Brake Quiet is a coating that sets up, not a grease lube.

 

i thought brake quite was for the pads, brake grease was for the sliders.

 

I was reefering to using the Brake Quiet on the pads. I thought that's where he put the grease.

 

Finally figured this one out! Found my drivers side rear caliper guide pin was loose and because of that it was missing most of its caliper grease. Tightened it, greased it, reassembled it and the noise is finally gone! I am ecstatic!