Little People Big World alums Jacob and Isabel Roloff's 4-year-old son, Mateo, was diagnosed with RSV. "My sweet boy came down with RSV, and it sent us to the ER last night with his oxygen as low as 80 and his heart rate as high as 180," Isabel, 29, wrote via Instagram on Sunday, March 8. "Is there anything more terrifying than seeing your kiddo not be able to breathe??" She continued, "I am just so thankful he's OK. We're home and healing! Here's to healthier days ahead." Isabel's mother-in-law, Amy Roloff, subsequently sent her prayers for a quick recovery.