Hello there,
It seems that you are suffering from some allergies or some form of vasculitis.It can be from an allergic reaction to something. The other possibility is
hives.
Hives are commonly the result of illness, food allergies, medications, insect bites, extreme temperatures and hypersensitivities to certain irritants. Take over-the-counter antihistamine like hydroxyzine for relief in symptoms. The rash definitely needs to be looked at and monitored by a physician.