Jack Kinnear is one of around 12,000 children in the UK affected by the debilitating disease, having been diagnosed with Juvenile Idiopathic Arthritis last year.
Defined as arthritis in children under 16, JIA causes swelling, stiffness and often excruciating pain in the joints.
The rare disease can be difficult to diagnose, and Jack's condition initially baffled doctors.
His mother Sonia Ewens explained: "We had noticed that Jack was limping slightly on his left leg and we took him up to the accident and emergency department to get it checked out.
"The doctors said he was fine and sent him home, but then two weeks later the pain in his leg returned. Once again he was sent home, however a fortnight later he was screaming in agony and crippled with pain.
"His knee was swollen and hot to touch. I had to carry him to the hospital where doctors finally diagnosed him with polyarticular chronic juvenile arthritis.
"I was shocked when we were told. I had no idea children could even get arthritis."
Jack, who also suffers from diabetes, is now receiving medication to control his arthritis on a daily basis.
Sonia (34) added: "They had to be sure of the diagnosis before they prescribed Jack's medication so we saw him in some terrible states. It was devastating for us as a family.
"The worst thing was watching him in so much pain and feeling helpless because there is nothing you can do about it. As a mother that is awful."
Jack's arthritis has been managed for the past seven months with drugs, and it is hoped the condition will eventually go into remission. The treatment has enabled him to lead a relatively normal life, and he keeps active with plenty of swimming and cycling and attends Pathhead Nursery.
Sonia and her partner Sandy (42), hope to raise awareness of the condition to give a better understanding of the disease.
"As parents we received more support for the diabetes than we did for the arthritis, however, we actually needed the help more for the arthritis," Sonia said.
"Not as much is known about arthritis in children, and watching your child go through such pain was very difficult for us as parents.
"One of our doctors has been great and staff at Jack's nursery have also been fantastic. If the arthritis does go into remission, there's no guarantee it won't return, but at the moment we are taking things day by day and hoping for the best."

The facts about juvenile arthritis...
JUVENILE arthritis is a relatively rare disease, affecting about 1 in 1000 children in the UK.
NHS Fife is currently treating around 60 children who have some form of juvenile arthritis, and the health board runs two weekly clinics at Victoria Hospital.
Consultant rheumatologist Dr Jane Gibson said: "Most people think of arthritis as an old person's illness but children can get various types of inflammatory arthritis which can have a huge affect on their lives."
The two most common types are Oligoarticular arthritis - causing swelling in four joints or fewer - and Polyarticular arthritis - affecting five or more joints.
The former can be treated with steroid injections, while the latter requires a drug treatment administered by weekly injections.
While there is no cure, the past ten years have seen developments in treatments which mean many children now go into remission.
"Where as before every aspect of a child's life would be affected - including permanent damage to their joints - now we have these new drugs, the outcome has completely changed," said Dr Gibson.
"Before it was a life-destroying disease, now we can get it into remission more easily."