Shania Twain opens up on 'devastating' diagnosis and feared she'd 'lost voice forever' amid Glastonbury backlash

Some of the issues were linked to Twain sounding bad, which left many confused as they penned on their social media that they knew "she can legitimately sing".

The issues may have stemmed from the Man! I Feel Like A Woman's previous issues with Lyme disease after experiencing frightening symptoms following a tick bite, causing her to blackout during performances.

The 58-year-old recently discussed the harrowing details of how her voice was altered by the illness during her Netflix documentary - Not Just a Girl - and said: "My symptoms were quite scary because before I was diagnosed, I was on stage very dizzy.

"I was losing my balance, I was afraid I was gonna fall off the stage... I was having these very, very, very millisecond blackouts, but regularly, every minute or every 30 seconds."

She continued, expressing the fear that gripped her: "My voice was never the same again. I thought I'd lost my voice forever. I thought that was it, [and] I would never, ever sing again."

Last year, the singer gave an update on her recovery and spoke about how grateful she felt to be able to return to singing and songwriting after the traumatic experience.

"It was quite depressing and devastating to imagine that [not being able to sing again]. Even speaking has been difficult with the Lyme disease. Now I'm just feeling so grateful that I can sing and express myself.

"And this now is my first album since the operation on my voice. You have to be awake while they do it. I was more afraid of never singing again than getting through the operation.

"The reason you have to be awake for the operation is that you have to sing during it so they know exactly what to do," she told ITV's Lorraine Kelly.

Despite her return to the music, she appeared to struggle through her Glastonbury set and appeared to forget the words to her hit songs You're Still the One, That Don't Impress Me Much and Any Man of Mine.

She insisted on the audience sing along with her and enthused between songs: "Well, before I move on - I want to say hats off to you, Glastonbury.

"I mean, I just have to say thank you for sharing the experience - this is wild. I've been walking around since last night, driving around and getting through the crowds and through the tents and villages and this really is a city and it's a community, and I do feel the privilege of being here, thank you very much for having me."

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Noticing how her vocals seemed off, some festival-goers and listeners at home took to their social media, leaving one to question: "Is Shania having trouble with her earpieces? #Glastonbury."

"Why does Shania sound so bad? She can legitimately sing?? #Glastonbury," another questioned before a third asked: "Is Shania Twain doing a tribute to Norman Collier's faulty mic sketch?! The sound is well off. #Glastonbury."

"I'm seeing Shania Twain next week at BST next week. Hoping she's better than this.... eek. #Glastonbury," one fan admitted.

"Shania Twain don't impress me much. Is she OK? #Glastonbury," another concerned fan asked as someone else shared: "Omg! Just turned on #Glastonbury and #ShaniaTwain sounds dreadful!"