The country singer's son wrote a heartfelt open letter on Instagram after that viral inauguration performance: "You’re not healthy Dad and everyone is noticing it."

Billy Ray Cyrus' son is sharing concern for his father's wellbeing. In an Instagram post Wednesday, Trace Cyrus, the 35-year-old brother of Miley Cyrus and son of Billy Ray Cyrus, wrote a message addressed to his dad and said that he is worried about him.

The 25-year-old Australian singer's comments follow Billy Ray's performance at Trump's post-inauguration Liberty Ball on Monday, January 20. During his two-song set, the country star was forced to sing his 1992 hit "Achy Breaky Heart" a cappella after what he later claimed were equipment malfunctions left him scrambling.