Jorja Austin, 40, was bitten by a gnat in 2009 while cutting the grass at her home in Basildon, Essex.
Now doctors have said the former admin assistant may need both legs amputated after suffering a life-threatening bout of sepsis.
Despite being just a “pinhole” size, the bite never healed and two years later Jorja was diagnosed with pyoderma gangrenosum, a rare skin condition that causes excruciating ulcers.
Jorja said: “I’ve been in agony for 13 years. At one point I could see my leg tendons.”
“There’s a risk that my legs will have to be amputated.
“But the doctors have said that the sepsis may heal so I might be able to get plastic surgery instead.
“I’m just hoping the wounds will get better. Fingers crossed it will all turn around.”
Jorja has spent three weeks at Basildon Hospital after being rushed there with sepsis and falling into a coma for 12 days.
Doctors are now keeping dressings on her lower legs, which are almost red-raw from painful ulcers.
Recalling the insect bite that happened in 2009, Jorja said: “I was in the garden cutting the grass and I literally had four tiny bites on my leg, just like pinholes.
“One bite never healed up. When I went to the doctors they said it was fine but it just got bigger and bigger.
“I was diagnosed with pyoderma gangrenosum two years later. I was just one of those unlucky people.”
Jorja has two children aged 12 and 16, who were put into social care as their mum’s health began to fail and authorities ruled her health meant she could not care for them.
Her sister Paige Austin, who has supported her, said: “She is the strongest person we know and has been the rock in our family.
“Even though she suffers so much herself, she always has wise words for us and is there when we need a shoulder to cry on.
“I feel traumatised seeing what she had to go through, as no one deserves to be treated like that.
“She’s still going strong but no one should be like this at the age of 40.”