Thanks for you patience.
You presented a history of
SLE, GFR at 56-55, left sided lower rib
pain recurring.
Regarding the
pain, is it tender to touch; does it change with movement; does it increase with deep respirations.
It would be prudent to think about a musculoskeletal cause or a pleuritis etiology (inflamation of the lung or inner chest wall lining). Occasionally,
SLE "flare-ups" present with pleuritic
pain.
Regarding the kidney concerns, commonly
SLE patients have kidney disease. It would be worthwhile to get a UA with microscopy, Bun, Cr, and a 24 hour urine if protein present on the UA.
Your family physician may consider
SLE as a source of both problems and test and treat accordingly including consult to nephrologist.
Let us know how things go.