Nicky Green, 40, from Dorset, said a delay in doctors diagnosing her son Finley Green with the rare lymph node syndrome Kawasaki disease, led to further complications.
She wants parents to look out for symptoms of the disease, which many people wrongly believe is restricted to children in the Far East.
She told Bournemouth Echo: "It is important to diagnose this as soon as possible. Fin has a couple of medium-sized aneurysms and one large one, but if his illness was identified sooner that might not be the case."
Finley went to the doctors in August 2015 as he was experiencing a fever, aching limbs and red eyes. His mother said he was then referred to hospital where doctors were unsure of his diagnosis.
Doctors removed Finley's appendix as they believed this could have been the cause of his illness, but his symptoms - including a raised temperature and chapped lips - still persisted.
It took 10 days for doctors to diagnose Kawasaki disease.
The NHS states Kawasaki disease is thought to be caused by an infection and it cannot be prevented, but if it is diagnosed and treated promptly most children can make a full recovery.
Finley spent eight weeks in hospital and now has regular check-ups to monitor his condition.
Finley gets tired easily and regularly has to test his blood with a pinprick.
Explaining the symptoms, Mrs Green said parents should look out for: raised temperature, red eyes and tongue, chapped lips and peeling hands and feet.
She urged parents to call their doctor straight away if they notice these symptoms in their child.
The NHS also states symptoms include a rash, swollen glands in the neck and red fingers or toes.
Medical experts believe more needs to be done to research and understand this disease.
Professor Michael Levin of Imperial College London told Bournemouth Echo: "Neither the public nor the medical and scientific community have adequately appreciated that Kawasaki disease is now the commonest cause of acquired heart disease in children in the UK and other developed countries.
"There is an urgent need for research to develop a diagnostic test for the disease, to identify the cause, and to evaluate new treatments."
A video documenting Finley's story has been shared on his school's Facebook page.