I am sorry you are flaring, I am too
and it sucks! This is the 2nd worse flare I've had, I've had little ones here and there but this one is BIG. I have been out of work since last Thursday and not feeling any better!
You may want to talk to your rheumy, your lupus may not be under control with your current meds. My rheumy added folic acid for my mouth sores, I take 3- 1mg tabs a day and it works well at keeping them away.
I hope you feel better soon!