Contact Syncing Issues

So here is my issue. First I have not changed any settings, but somehow I have a new mystery problem. My contacts are no longer syncing between my devices. My iPad and iPod sync together, but my iMac and iPhone are not. It's rather annoying! I entered a new contact in my ipad which then usually syncs to my other devices. That contact made it to my iPod, but not my iPhone or iMac. I made sure my contacts were turned on, on the various devices. They were all turned on. I then took my iPhone turned off the contacts and let it sit for a few minutes. I then turned them back on and the contacts repopulated, but my iPod and iPad are the only two with this particular contact. What am I missing?