Are you still on any Plaquenil? I know that quinine products can cause your condition and also aggravate it. I do hope that the trace of nickel is not the culprit because then, there is little that you can do about it. I've never had this condition, but my brother has suffered with it for years and years. His remedies are often quite curious, but they work for him. When the DE is really bad, he puts a cloth on the area and irons it with a steam iron. He says that it actually works. He also said that taking extremely hot showers (no soaps or any chemicals..just hot water) also helps him. He does not use over-the-counter laundry detergents, body soaps, shampoos, or deodorants. He said that he has to buy all natural products at the health food store and/or online. They can't contain any chemicals or dyes at all.
Like you, he has periods when it is active but not aggravating. Then he has periods where he is suffering greatly because it is all over his body (elbows, neck, back of knees, feet, palms of his hands, his shins, his back, and his stomach). I feel so sorry for him at those times because there is nothing to be done to help him.
I did, on one occasion when he was visiting us, help him do the steam iron thing and after a few hours, the rash cleared up. I don't know what it is about heat that relieves his symptoms, but it does.
I do hope that you find some relief and that it does not get any worse. On top of everything else huh?
Take care of yourself..Sending you warm hugs
Peace and Blessings