Brett Eldredge says he has tested positive for breakthrough COVID-19.The country music artist, 35, took to Instagram on Thursday to reveal his positive test, which resulted in him rescheduling a pair of concerts he was slated to play at the Chicago Theater on Friday and Saturday on his Glow Live tour.Eldredge said he had a 'really rough day' after he felt as if he'd caught 'a cold or something the last few days.' The latest:Brett Eldredge, 35, says he has tested positive for breakthrough COVID-19 in an Instagram post on ThursdayHe said of the concert, 'I've been so excited about playing this show, and I know a lot of you have been excited to go to it.