Dawn French has revealed doctors were worried she may have had a brain tumour after she become unwell during her 2014 stand-up tour.
Thankfully, the actress, 64, didn't have a tumour, but described feeling like her head was "collapsing inwards" during the illness.
It turned out that she had vertigo during the 30 Minutes tour and she was forced to take a stick on stage as she feared falling over on set.
She explained how scared she was by the condition and confessed that it was triggered by the harsh lighting on the stage.
Dawn opened up on her experience on Michelle Visage's Rule Breakers podcast on BBC and revealed: "It is like my skull is a room and the whole of the top is collapsing inwards, and everything starts spinning.
"It's like being very drunk and not understanding what is up and what is down. And for a while they thought I might have a brain tumour."
She went on to say how neurologists informed her that side-lighting on the stage is what triggered the issue, saying the darkness in front of her meant she had nothing to latch her eyes onto.
The stage she performed on had a slope down towards the crowd, meaning her body didn't feel as though she was upright and worsened her condition.
The Vicar of Dibley actress continued: "I took a stick on stage with me and I would make my two legs very wide on stage and I would put the stick in front of me like a tripod so that I had something to stand up to.
"It was like being on a buffeting boat or something. It was awful, absolutely awful."
She was given Beta blockers in a bid to calm her fear of toppling on stag and revealed it made the situation worse.
Thankfully, the condition disappeared several weeks after she completed the tour, but she still fears if it will ever return.
"When you ask me if I have nerves, I have good nerves about the show, I have not so good nerves about that kicking off again because if it kicks off I know that I'm in hell, holding on to walls," she said.
Earlier in the month Dawn also admitted she wasn't Jennifer Saunders' biggest fan when they first met.
She said: "I didn't really like Jen that much at the very beginning because she's quite posh, or I thought she was but she's not really. She had a whole friendship group of way out of my league sort of people, and then I had to share a flat with her.
"But as soon as I got rid of my prejudice about her, which I still have to this day - prejudice against posh people, they have to prove their worth to me - I thought, 'She's actually great."
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