Lauren Boddy, from Reading, spotted a red bite mark with a blister appearance in the centre on her leg in May this year.
But the next day, she couldn't put any weight on her leg, and realised the spot was bigger and full of pus.
She went to her doctor, who prescribed her a course of antibiotics.
The 27-year-old told the Mirror: "Within two days it had changed colour, swollen up so I went to hospital. They prescribed more antibiotics because they could tell it was either fangs or claws and they even asked if I had been abroad.
"A couple of days after that I was shivering, I had a high temperature. I went to hospital and they admitted me straight away."
At the Royal Berkshire Hospital Miss Boddy was given x-rays to check for bone infections, and was tested for blood poisoning. She was put on a