It's not Kawasaki disease it's
Henoch-schoenlein (sp) purpura. I know this because my son had it when he was four.
It happens after a respiratory illness the antigens created by the body to defend against the viruses bacterium bind with the the invader. This is supposed to happen, but instead of destroying the virus and breaking it apart, they remain bound together.
Because of gravity, the large particles collect in the extremities. The body tries to get rid of them, so it sends them out to the skin. Unfortunately, they cause the small capillaries to burst causing swelling, a rash like bump, and then vasculitis, a red mark from escaping blood.
It causes this wherever there are tiny capillaries and is dangerous because it CAN cause permanent damage to the kidneys.
It is hereditary, mostly, rare, and generally found in people/children of Scandinavian heritage.
It can happen after ANY severe respiratory disease. Colds, flus, croupe… etc.
Treatment is plenty of water and you have watch the urine for blood… blood equals kidney damage. It can take up to a month to flush out all the large particles.
Other symptoms are swollen joints and pain when walking. Sudden high fever.