Carrie Underwood suffered a nasty fall when she performed at the Carolina Country Music Fest in Myrtle Beach in early June. After saying goodnight to everyone, she exited the stage — but seemed to drop through a hole in the floor! In a video posted by TMZ, the country star, 41, was drenched from the rain when she fell over. Someone in the crowd said, “She fell!” After the incident, the blonde beauty took to Instagram to brush off the incident. “We won’t let a little rain stop us! We won’t let a massive downpour stop us, either! 🎥: @jeffjohnsonimages @ccmflive #MyrtleBeach #SingingInTheRain,” s…