It sounds like some type of vasculitis which may have been with you even as a child. Vasculitis can be due to too many things to enumerate. Leukemia, Kaposi's sarcoma, Kawasaki Disease (gamma globulin would probably have been given to curtail it then), an infectious process of some sort, an immune disorder (like juvenile RA), a medicine reaction, even a food allergy never identified but in which the food substance is still ingested. Not saying you need allergy testing which if you have an inflammatory process going might show positive results in all directions, but there is some underlying thing to which the key is incidence since childhood. You probably need a specialist experienced in infectious disease as well as immunological disorders.
