Maren Morris had "the worst sinus infection" days before her New Year's Eve performance.
The 35-year-old pop-country star's face "swelled up" and had to fight off the serious health ordeal prior to entertaining the crowd in Times Square, New York, with her hits, such as The Bone, The Middle, and 80s Mercedes, during Dick Clark’s New Year’s Rockin’ Eve with Ryan Seacrest on December 31.