Justin Bieber is letting fans know why he had to postpone a series of concerts recently, revealing he has been diagnosed with Ramsay Hunt syndrome.

"It is from this virus that attacks the nerve in my ear and my facial nerves. It has caused my face to have paralysis," he explained in a video shared on Instagram Friday.

Bieber then showed how it has affected the right side of his face in the video, sharing "This eye is not blinking. I can't smile on this side of my face. This nostril will not move. So there's full paralysis on this side of my face."

Ramsay Hunt syndrome is caused by the chickenpox virus, which continues to lay dormant in a person after initial infection and can reactivate as a shingles rash, according to the Mayo Clinic. The syndrome is caused when a shingles rash, which can be painful, breaks out near one's ear. It can trigger facial paralysis and hearing loss.

@gma #JustinBieber just announced his diagnosis with #ramseyhuntsyndrome. Dr. Leah Croll gives us more information. #bieber #health #medicine #doctor #doctorsoftiktok ♬ original sound - Good Morning America

The Grammy winner had a message for fans who feel "frustrated" that he had to call off several shows.

"I'm just physically not capable of doing them. This is pretty serious ... I wish this wasn't the case," he said. "I hope you guys understand."

The singer assured fans he's using this time to rest and recover, "So that I may do what I was born to do." He also revealed he is doing "all these facial exercises" so that he can get his "face back to normal."

Bieber said he doesn't know when he will be recovered enough to resume his tour and thanked fans in advance for their patience. "It's gonna be OK," he said. "I have hope and I trust God and I trust that it's all for a reason and I'm not sure what that is right now."