Henoch-Schonlein purpura (HSP) is a disease involving inflammation of small blood vessels. It most commonly occurs in children. The inflammation causes blood vessels in the skin, intestines, kidneys, and joints to start leaking HSP is caused by a problem with your immune system, possibly as a result of a previous infection. It has been known to occur after a bacterial orviral infection of the throat, airways or lungs (respiratory tract infection). HSP cannot be spread from person to person and doesn't usually run in families.
I had this as a child .. thankfully no lasting problems or kidney troubles