I've noticed that after I do a coffee enema at night, I develop lower back pain. The enema stimulates the liver in the same way that molybdenum and milk thistle do; it could be that the stimulation causes the liver to work harder and therefore dump more toxins into the bloodstream, thus irritating or putting a burden on the kidneys to eliminate them through the urine faster.
I don't have experience with or enough knowledge about Lupus to tell you what's going on, though. Try verifying with other commenters or asking them what you can do to help your kidneys. On that subject, I'm not very knowledgeable either.