As long as you're looking at lupus because of the sun rash, you could look at the porphyrias as well (you wouldn't even want to know how many case reports there are of people who have been diagnosed with both lupus and a porphyria -- it seems as if they'll diagnose both when in doubt ).

I doubt a porphyria would give you a higher sed rate but you could get diarrhea, a lot of pain, trouble breathing, a sun rash, anemia, high blood pressure, tachycardia, some kidney problems, and difficulty walking (+ a lot of other neurological symptoms) with it.