The Oscar-nominated Silver Linings Playbook star had been battling pneumonia for weeks when she discovered her breasts were noticeably uneven in size during a routine chest x-ray.
"I just went to the doctor and I got a chest X-ray of my lungs and discovered that my breasts are uneven. That was all I saw," she told Kimmel.
"I was, like, standing there with these doctors and they're, like, looking at my lungs... and it felt like an elephant in the room and I was like, 'Are my breasts uneven?' They were just kind of like stifled and uncomfortable, obviously, and so I kept thinking, 'Well, I'm gonna dig myself out of this hole by bringing it up again...
"Are you worried about that? Is that a concern?" Kimmel asked.
"It wasn't until the X-ray. I just hope no one will ever see my breasts in an X-ray," the actress joke in an answer.
But she's glad her fever is over, because she was so hot and drugged up at the 2013 Golden Globe Awards last month she missed out on the chance to chat to her favorite singer Adele.