Proteinuria is usually treatable with an ace inhibitor like lisinopril.
I had it and it caused rather severe edema. A neprologist will probably want to do urine tests (24 hour) and a kidney biopsy. Had all of them and found stage 2 damage. After treatment with lisinopril my kidneys have returned to normal. It will take a few months if the damage is not bad.
Don't anticipate but make an appointment soon. Make sure the nephrologist is familiar with lupus.
Bill