After enduring four years of agony and dozens of blood transfusions and skin grafts that amounted to over $1 million in medical costs, a Michigan woman has finally recovered from a spider bite.

Jane Hefferan of Dearborn, Michigan, said that she would have brushed off the redness and pain she was feeling in her knee if her physical therapist had not forced her to take it seriously, according to WDIV-TV in Detroit. "He's like, 'you need to go to the emergency room,'" she said, according to the TV station.

She said that she would have never guessed that a single spider bite would turn out to be significantly more serious. Doctors believe that Heffernan may have been bitten when an extremely poisonous brown recluse spider crawled into her bed in Nashville. Experts say that 38 percent of brown recluse bite cases occur when victims are sleeping.

The bite had immediately swelled up her knee but she had shrugged it off as a previous running injury because she was too busy studying for the bar exam to worry that something was wrong. "My knee got red. It looked just like a bruise at first," said Hefferan. "It was all underneath the skin, and my knee was really swollen too. It kind of had a burning feeling."

She had blamed the bite on a previous stress fracture in her foot, but her physical therapist, who had realized that it was something more, insisted that she go to the emergency room immediately. When she arrived at the emergency room, doctors said that she may have been bitten by a spider.

"I immediately said that no it wasn't a spider bite. It couldn't possibly be.  I had no idea that a spider could do something like that," said Hefferan. Doctors had given Hefferan antibiotics and performed surgery to strip off the first layers of dead tissue from her knee, her leg just kept getting worse.

"The initial surgery was just to cut out all of the necrotic or dead tissue that the spider had destroyed," said Hefferan.  "It was on the side of my knee. They cut down basically to the lining of the bone." She had needed skin grafts to cover the wound but they wouldn't heal and she continued to bleed and wound up. Later, doctors discovered that this was due to an autoimmune disorder called pyoderma gangrenosum that she is being treated for.

To make matters worse, during her recovery from the first bite, doctors noticed that she had suffered another bite on her other leg, which proved to be even worse. "It was eating up so much of my leg, and so much of my tissue was gone," she said. "At that point there was like nothing left of my leg. It was just basically bone."

While doctors ultimately were able to save Hefferan's legs, she had to spend several weeks in the hospital and undergo more than 20 surgeries and dozens of blood transfusions over the next four years that amounted to over $1 million before she was able to fully recover. Even though she had just graduated from law school when her nightmare began and has since passed the bar exam despite her injuries, Hefferan believes that the experience may have permanently changed her future.

"It's completely changed the course of my life, and it's changed my career," she told WDIV. "I'm now going back to school and hope to start a nursing program next fall."