Tommy Hilfiger's daughter says Lyme disease has "taken over every single cell" in her body and brain.
Ally Hilfiger - the oldest child of the fashion icon - has admitted her battle with the debilitating illness has left her feeling like an "80-year-old woman" after doctors failed to spot the infection for 14 years after she contracted it.
Speaking to the Daily Mail newspaper, she said: "I couldn't put lotion on my legs because it felt as if I was being beaten with a baseball bat. I was like an 80-year-old woman. It had taken over every single cell in my body and in my brain."
The 30-year-old fashion heiress believes she was plagued with the disease after she was bitten by a tick as a child.
The illness, which is passed on to humans via an infected tick, left Ally in "excruciating" pain, which led to her relying on a walking stick and struggling to sleep at night time.
Doctors initially thought Ally's symptoms - which included painful joints, headaches and a high fever - were pointing towards arthritis, a sever case of flu or growing pains.
However, Ally was adamant her symptoms were caused by something more sinister and sought a second opinion from a psychologist, who diagnosed her with the chronic disease.
She said of her diagnosis: "This was like winning the lottery for me. I was so relieved."