"I could just tell there was something wrong, and something more [serious], so I was like, 'He needs to see a doctor!'" she recalled. "I was the one who was like we need to get him to a doctor.'"
"His cough was so deep," Brie chimed in. "And it still hasn't gone away."
As Nikki explained, Artem is "crazy fit" from his work as a DWTS pro and tour dancer, so he's in peak physical condition, which should have helped him overcome his illness.
"So, it's been scary for a while, and we're just hoping it heals because it's his lungs," she explained.
Artem took to Twitter earlier this month to share a health update with fans, and revealed that he'd been put on a second round of antibiotics to help combat his pneumonia.
"So, I had another X-Ray done yesterday and it came back still positive for pneumonia," he explained. "So I just got another set of antibiotics. This is of course number two. Hopefully this one will do the magic, will do the trick to kick out pneumonia out of my lungs."
In January, he was forced to step away from DWTS after announcing some "unexpected health issues." At the time, Artem took to Instagram and said he would be leaving the tour for a while with the hopes of recovering and rejoining the tour's cast and crew "as quickly as possible."
A rep for the tour told ET that the tour is continuing as planned and that they look forward to welcoming Artem back "in the very near future."