"Everything is fine. I'm good," Rivera said. "When it comes to my head, I'm worried. I have to check. I don't like to feel headaches. I just wanted to know what it was; I wanted to know what was going on."
The Yankees sent Rivera for a CAT scan and blood test as a precaution.
"We're not worried at all," Yankees general manager Brian Cashman said. "We have to follow certain protocols. He mentioned he was having some migraines, so there's a fire drill you have to run through just to be cautious.
"So we did that, expecting the results to be negative, and they were. So there's no issues. He might have the migraines, but they're not anything. All those tests were good."
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.