iPhone 5 music sync issues

When I got my iPhone 5 a few months back, I used my iCloud account for it, and my Apple ID for my Macbook. I synced music from my computer (ripped CDs and songs bought through my Original Apple ID) just fine with no issues with license authorization problems. I decided a few weeks back to use my iCloud account to try to start buying music from the iPhone to see how it reacted with the computer and if there were any licensing issues, which there were none. Once I got back onto the macbook and authorized my iCLoud account on the computer, random songs I had bought a few days ago WILL NOT PLAY on either device, which is very confusing to me. Somone explain what is going on?