Rash starts with white pustule, evolves into itchy cigarette burn style rash. had it for years on back and legs?

Sounds like Impetigo: This sounds like impetigo, a bacterial infection of the skin caused by staphylococcus aureus or streptococcus pyogenes. Have your doctor culture a lesion and inside your nose. If a culture is positive topical treatment and decolonization would be indicated.

See dermatologist: Although you may have an infection issue, it is unusual to have it evolved into an itchy rash. Consult your dermatologist who may consider a skin biopsy on a few of the fresh lesions. I would also recommend that you get a blood test for your vitamin d3 level as well.